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5.18: Biogeography - Biology

5.18: Biogeography - Biology



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Why would geography have anything to do with evolution?

Similar to "how did the chicken cross the road?" but on a much grander scale. How did the animal cross Europe and into Asia? Or Asia into America? How did anything get into Australia?

Evidence from Biogeography

Biogeography is the study of how and why plants and animals live where they do. It provides more evidence for evolution. Let’s consider the camel family as an example.

Biogeography of Camels: An Example

Today, the camel family includes different types of camels. They are shown in Figure below. All of today’s camels are descended from the same camel ancestors. These ancestors lived in North America about a million years ago.

Camel Migrations and Present-Day Variation. Members of the camel family now live in different parts of the world. They differ from one another in a number of traits. However, they share basic similarities. This is because they all evolved from a common ancestor. What differences and similarities do you see?

Early North American camels migrated to other places. Some went to East Asia. They crossed a land bridge during the last ice age. A few of them made it all the way to Africa. Others went to South America. They crossed the Isthmus of Panama. Once camels reached these different places, they evolved independently. They evolved adaptations that suited them for the particular environment where they lived. Through natural selection, descendants of the original camel ancestors evolved the diversity they have today.

Island Biogeography

The biogeography of islands yields some of the best evidence for evolution. Consider the birds called finches that Darwin studied on the Galápagos Islands (see Figure below). All of the finches probably descended from one bird that arrived on the islands from South America. Until the first bird arrived, there had never been birds on the islands. The first bird was a seed eater. It evolved into many finch species. Each species was adapted for a different type of food. This is an example of adaptive radiation. This is the process by which a single species evolves into many new species to fill available niches.

Galápagos finches differ in beak size and shape, depending on the type of food they eat.

Eyewitness to Evolution

In the 1970s, biologists Peter and Rosemary Grant went to the Galápagos Islands. They wanted to re-study Darwin’s finches. They spent more than 30 years on the project. Their efforts paid off. They were able to observe evolution by natural selection actually taking place.

While the Grants were on the Galápagos, a drought occurred. As a result, fewer seeds were available for finches to eat. Birds with smaller beaks could crack open and eat only the smaller seeds. Birds with bigger beaks could crack and eat seeds of all sizes. As a result, many of the small-beaked birds died in the drought. Birds with bigger beaks survived and reproduced (see Figure below). Within 2 years, the average beak size in the finch population increased. Evolution by natural selection had occurred.

Evolution of Beak Size in Galápagos Finches. The top graph shows the beak sizes of the entire finch population studied by the Grants in 1976. The bottom graph shows the beak sizes of the survivors in 1978. In just 2 years, beak size increased.

Summary

  • Biogeography is the study of how and why plants and animals live where they do. It also provides evidence for evolution.
  • On island chains, such as the Galápagos, one species may evolve into many new species to fill available niches. This is called adaptive radiation.

Explore More

Use this resource to answer the questions that follow.

  • Biogeography: Wallace and Wegener at http://evolution.berkeley.edu/evolibrary/article/history_16.
  1. What is biogeography? What scientist helped found the modern science of biogeography?
  2. Where did Wallace collect much of his data?
  3. What did Wallace study?
  4. What was the proposal of Alfred Wegener?
  5. What was Gondwanaland?

Review

  1. Define biogeography.
  2. Describe an example of island biogeography that provides evidence of evolution.
  3. Describe the effects of the drought on the Galápagos Islands observed by the Grants.

Global distribution of forest soil dictyostelids

Department of Natural Science, Manatee Community College, P.O. Box 1849, Bradenton, FL 34206, U.S.A.

Department of Environmental and Plant Biology, Ohio University, Athens, Ohio 45701, U.S.A.

Department of Environmental and Plant Biology, Ohio University, Athens, Ohio 45701, U.S.A.

Department of Natural Science, Manatee Community College, P.O. Box 1849, Bradenton, FL 34206, U.S.A.

Department of Environmental and Plant Biology, Ohio University, Athens, Ohio 45701, U.S.A.

Department of Environmental and Plant Biology, Ohio University, Athens, Ohio 45701, U.S.A.

Summary

AimThe goal of this project was to compile, organize, and present the known distributional data on the dictyostelid cellular slime moulds (CSMs) found in forest soils worldwide. The question of what factors influence CSM distribution patterns was also addressed.

LocationCSMs have been recovered from soils of temperate deciduous forest, tropical deciduous and seasonal evergreen rainforest, boreal coniferous forest, and tundra by various investigators around the world.

MethodsWithin each of these four biomes, various locations around the world have been sampled by a number of investigators. The current study attempts to synthesize the known dictyostelid distributional data and present specific patterns of distribution.

ResultsWorldwide, sixty-five species of CSM were found to occupy various forest soils. These species’ distributions fell into one of four categories: cosmopolitan, disjunct, restricted, and pantropical.

Main conclusionsGlobal CSM distribution patterns are influenced by a variety of factors other than the biota (including but not restricted to climate, latitude, altitude, soil pH, and soil-forming parent materials). The current study supports the thesis that organic inputs from specific plant associations and animal vectors have an important role as well.


Background

Mediterranean freshwater fish fauna is characterized by a relatively low number of fish families, with most of the species belonging to Cyprinidae [1, 2]. In effect, this family is among the most speciose families of freshwater fishes and likely to be one of the largest vertebrate families [3]. The family Cyprinidae also features a relatively high number of endemic species on the Mediterranean slope [2] and its wide biological and ecological plasticity has bestowed this group an important role in biogeographical models [4–7]. As dispersion mechanisms are highly restricted in primary freshwater fishes [8], their distributions are directly related to paleogeography and relationships among different areas [9–11]. Thus, phylogenetic relationships among evolutionary lineages reflect the history of cyprinids within the Mediterranean region.

The classification of cyprinids has always been a matter of controversy and from 2 to 12 subfamilies have been recognized depending on author and the morphological traits considered [12–15] and even have been recently elevated to family level, being assigned European and North American leuciscins and phoxinins to the new called family Leuciscidae [16, 17]. Traditional morphology, however, sometimes conflicts with the more recent molecular studies [5, 18–23] because some morphological characters are prone to homoplasy [5] and usually there is unclear homology of morphological traits [24, 25]. This determines that recognized monophyletic groups are clearly misinterpreted. In this paper, we followed the classification scheme of Saitoh et al. [22] based on complete mitochondrial genomes. These authors consider the subfamily Leuciscinae exclusively formed by the Eurasian and North African leuciscins (including the North American genus Notemigonus, as the only known representative in this region) and promote phoxinins [15] to their own subfamily, Phoxininae, as the sister group of the subfamily Leuciscinae. To date, however, the nuclear phylogenetic relationships of cyprinids, and particularly leuciscins, have been little explored [26, 27].

The fossil record of Cyprinidae family in Eurasia [28–30] suggests its origin in East and Southeast Asia, where greatest generic and species diversity is found [1, 3, 31]. This group then colonized Europe for the first time during the Oligocene period when the Ob Sea disappeared because of the uplifting of the Urals, and reached the Iberian Peninsula (the westernmost part of Europe) in the late Oligocene-early Miocene [32]. The colonization of North Africa has been explained by connections with Iberian and Asian fish faunas during Cenozoic period [33]. Within the family Cyprinidae, the subfamily Leuciscinae may be used to test biogeographical hypotheses for the Mediterranean basin. In addition, owing to its long-standing distribution range in the Circum-Mediterranean area it should be possible to unravel the evolutionary history of this group.

Traditional hypotheses have proposed the origin of the subfamily Leuciscinae in the Mediterranean area and its subsequent diversification through river captures from central Europe as several waves stretched across a long time period (from the Oligocene until late Pliocene, 35-1.7 mya) [34, 35], following the hydrogeographical and geological history of the European area [36]. This model has been designated as the "north dispersal model" [37]. Hypotheses opposing this model have argued that the colonization of Circum-Mediterranean rivers cannot be explained by a northern route. The alternative model proposed is based on leuciscine dispersion during the lacustrine stage of the Mediterranean basin [38], when this sea became refilled with fresh water from Paratethys Sea during the Messinian salinity crisis [39]. This would have allowed Paratethyan freshwater icthyofauna to colonize the Mediterranean margins. This hypothesis is described as the "Lago Mare" dispersal model [38]. The later opening of the Straits of Gibraltar [40] filled the Mediterranean area with marine water, with the subsequent isolation of the new-formed freshwater populations along with intense vicariant events [41, 42]. However, the Lago Mare and north dispersal hypotheses are not mutually exclusive and together could have played an important role on dispersal of cyprinids across Europe [1, 11, 43]. On the other hand, the Middle East has been considered an important interchange area for freshwater ichthyofauna during the gradual closing of the Tethys Sea [6, 44, 45]. It is in fact held by some authors that the Middle Eastern freshwater fauna is made up of species that came from Asia and more recently from Euromediterranean ancestors [6, 45, 46]. The basis for this latter proposal is the close affinity found between Middle Eastern and Euromediterranean cyprinids [6, 47]. This region has been also recognized as a center of origin for some Leuciscinae species [6, 11, 48].

Most recently, Pleistocene glaciations influenced the distribution of Leuciscinae representatives, especially in North and Central Europe, where some species became locally extinct when the region was covered by ice [35, 49]. Later recolonization from eastern refuges such as Circum-Black Sea drainages has been suggested to explain the wide distribution of some extant cyprinid species [11, 50, 51]. Although the Mediterranean Peninsulas and Caspian/Caucasus region are known to have acted as glacial refuges [52, 53], the Iberian, Italian and Balkan Peninsulas were isolated from northern and central Europe because of the Alps uplift during the Pleistocene thus preventing most Mediterranean freshwater species moving northwards. This interpretation explains the low level of shared freshwater species between north-central and southern Europe.

Weighing up all biogeographical scenarios, some models have attempted to explain the center of origin and the main dispersion routes for cyprinids [1, 6, 11, 34–36, 47, 48, 54, 1], while others have tried to identify barriers to explain the vicariant patterns observed in cyprinid fishes [4, 5, 14, 25, 32, 33, 37, 43, 55]. Despite these efforts, the phylogenetic relationships of Circum-Mediterranean leuciscins and their biogeographical patterns in Mediterranean area remain unclear.

To obtain reliable information on the mitochondrial phylogenetic structure of this group, the comprehensive study examines mitochondrial DNA in numerous species of the subfamily Leuciscinae. Indeed, sequences of the cytochrome b (cyt b) gene have achieved phylogenetic resolution in some fish groups [56, 57], including cyprinids [4–7, 11, 18, 20, 37, 43, 48, 58]. In turn the cytochrome oxidase I (COxI) gene has also proved to be a useful tool for the identification of fish species [59, 60]. Here we complete the mitochondrial phylogeny of the subfamily Leuciscinae using nuclear information by analyzing the Recombination Activating Gene 1 (RAG-1) and the Ribosomal Protein Gene S7 (S7). Only a few previous molecular studies on cyprinids have yielded a nuclear phylogeny of Circum-Mediterranean representatives of the subfamily Leuciscinae. Some leuciscine groups have been examined using nuclear allozymes [10, 61, 62] or DNA sequences [63–65] approaches and some phylogenetic relationships have been proposed for cyprinids [66]. However, this paper constitutes the first attempt at deciphering the nuclear relationships of the main Mediterranean Leuciscinae lineages based on sequences data.

The aim of this exhaustive study was to investigate phylogenetic relationships among the major Circum-Mediterranean Leuciscinae lineages by analyzing sequence variation of both mitochondrial (cyt b and COxI) and nuclear (RAG-1 and S7) genes. Data were obtaining for 321 individuals representing 176 species of the subfamily Leuciscinae and 9 outgroup species. The data were used to test for biogeographical events that could have determined the distribution of leuciscins in Mediterranean area.


PhD Candidates

My work heavily relies on genomic data and the main study system I work on is the genus Triturus, the crested and marbled newts. I am particularly interested in the evolutionary history of closely related species – how such species originated and obtained their current distribution and how they interact during the course of their evolution, as ecological divergence drives them apart and gene flow pulls them together. My early work mainly involved phylogeography (inferring glacial refugia), systematics (resolving rapid radiations) and taxonomy (diagnosing cryptic species). Recently, I have been studying hybridization, both under natural conditions (in particular hybrid zone movement) and anthropogenically induced (the complicated conservation issues of ‘genetic pollution’). Presently, I am conducting a research program, funded with an ERC Starting Grant, aiming to understand the evolution of balanced lethal systems. Balanced lethal systems are extremely maladaptive as they cut reproductive potential in half. Yet, they have evolved time and again along the branches of the tree of life. I hope to solve this evolutionary mystery.


Anthropogenic drivers altering metacommunity processes

The main global anthropogenic drivers of biodiversity change, and thus the main conservation challenges for the 21st century, include land-use change and water management (including habitat loss and fragmentation), climate change, biological invasions, pollution, and overexploitation. 59-61 Because we advocate for a process-based perspective on metacommunity assembly, we discuss below how these global drivers affect metacommunity processes in multiple ways, which in turn influence the biodiversity variables of interest (Fig. 2). For example, changing climate and physicochemical properties directly influence environmental filtering changing regional biotas and biological invasions alter biotic interactions and changing landscapes affect dispersal among habitat patches. Furthermore, demographic stochasticity and ecological drift can amplify the effects of other drivers by altering local extinction probabilities of small populations affected by a given anthropogenic pressure. Although there is still a long way to go to fully understand the effects of disturbance on metacommunity functioning and in turn on biodiversity, we identify some general mechanisms for each of the main global change drivers.

Land-use change and water management

Land-use change, such as habitat fragmentation and loss, directly alters habitat and landscape properties, which in turn directly affects dispersal and environmental filtering. A prominent example is urbanization and road expansion, resulting in habitat fragmentation and connectivity loss. 62 Likewise, water-management intensification, including dam construction and water flow modification, is an intense driver of change in aquatic metacommunities. 63, 64 In both terrestrial and aquatic environments, these changes affect dispersal and habitat suitability. 65-67 Therefore, the metacommunity perspective can offer tools for understanding complex effects of land-use change for both terrestrial and aquatic conservation in the face of anthropogenic pressures. 68, 69

Climate change

Climate change directly affects metacommunities as an environmental filter, but also indirectly via complex community assembly processes and interactions. Species are extirpated from habitat patches and regions by climatic filtering if they are not able to adapt or disperse to regions with suitable climatic conditions. 70 Changing regions experience both emigration and immigration of individuals, which leads to compositional change and the emergence of novel biotic interactions. For example, a field experiment showed that novel competitors arriving from lower altitudes strongly reduced the performance of plants that failed to disperse upward to colder climates (in contrast to transplanted plants that could track environmental change). 71 Another indirect biotic effect of climate change is the phenological mismatch between consumers and associated trophic resources, 72 which may also affect dispersal if the synchronization between dispersal vectors and propagule production is affected. 73 Similar phenomena are discussed in both marine (e.g., Refs. 74 and 75 ) and freshwater (e.g., Refs. 76 and 77 ) ecosystems where shifts in species abundance, timing in phenology, and displacement of suitable habitats result at the metacommunity level in changed niches, modified dispersal/migration paths, and new species interactions.

Biological invasions

Invasive species directly impact biotic interactions in the metacommunity. Nonnative species compete with native species for resources, potentially reducing their performance and causing regional extinctions, as observed in both plants 73 and animals. 78 Likewise, invasive species can establish novel trophic interactions, such as predation 79 and disease. 80 Examples of invasion-driven extinctions are particularly prominent on islands, where species are often evolutionarily naive to these sorts of interactions. 81 In addition, invasive species can be physical ecosystem engineers, having profound effects on habitats that create environmental filtering for native species (e.g., invasive worms 82 and bivalves 83 ).

Pollution

Pollution causes habitat alteration and degradation, working directly as a strong abiotic filter through effects on fitness (via changes in growth, health, and behavior). 84, 85 It also affects habitat connectivity and suitability by increasing matrix hostility 86, 87 and reducing services, such as pollination (e.g., lethal toxicity due to pesticides 88 ). Pollution, especially via pesticides, can also interact with spatial processes within metacommunities to repeatedly and cumulatively influence impact, recovery, and regeneration processes. 89, 90

Overexploitation

Overexploitation directly affects mortality, decreasing population size and consequently population viability. 91, 92 This effect is exacerbated by associated demographic stochasticity, which can lead to exploited populations experiencing higher levels of uncertainty, 93 particularly under environmental change. 94 Moreover, overexploitation can lead to entire community and ecosystem collapse through the breakdown of dependent biotic interactions if resource exploitation interferes with the trophic structure of communities (e.g., fisheries 95 ).

We here stress that the core metacommunity processes are the foundations for a mechanistic approach to understanding and managing the effects of such global change drivers on biodiversity (Fig. 2). However, evidence for the impact of global change on metacommunity processes and functioning has been largely circumstantial. Among the relatively few studies that have explicitly used a mechanistic approach, generalities have been elusive because anthropogenic drivers influence metacommunity functioning in multiple, often interactive, ways. 96-100 This is corroborated by meta-analyses showing that responses after disturbance are highly variable, and depend, among other things, on the type of disturbance, habitat, and trophic role. 101-103 Therefore, to understand global change effects on the conservation of populations and biodiversity, we need to understand how each metacommunity process, alone or in concert, is altered by these global change drivers.


5.18: Biogeography - Biology

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Taxonomy, Biology, Biogeography, Evolution and Conservation of the Genus Erikssonia Trimen (Lepidoptera: Lycaenidae)

A.J. Gardiner, 1,* R.F. Terblanche 2

1 1Organization for Tropical Studies, School of Animal Plant and Environmental Sciences, University of
2 2School of Environmental Sciences and Development, North-West University, Potchefstroom Campus, Priv


Systematics and Biogeography of the American Oaks

Paul Manos

Published May 2016 in International Oaks No. 27: 23–36

Abstract

The major groups of American oaks will be discussed with reference to phylogenetic patterns and newly resolved species alliances within the sections Quercus (White Oaks) and Lobatae (Red Oaks). Recent analyses of the nuclear genome based on extensive sampling across approximately 150 species suggest that oak species are mostly cohesive and compose geographically defined morphological groups. However, compelling evidence has been detected for ancient and current hybridization within section Quercus. Genomic data confirm our expectations when localized hybridization is suspected based on morphology and geographic proximity, but these data also point to more cryptic scenarios involving historic interbreeding among geographically disjunct and distantly related species. The biogeographical history of section Quercus in the Americas is highlighted by two independent intercontinental disjunctions, with the Eurasian species Quercus pontica to the Roburoid group. Within the Americas, sections Quercus and Lobatae share strikingly similar biogeographic histories, supporting originations and deeper evolutionary splits at higher latitudes, followed by more recent parallel dispersals and diversifications south to Mexico and Central America.

Keywords

phylogeny, Quercus, Lobatae, Protobalanus, Virentes, Ponticae

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Environmental protection could benefit from 'micro' as well as 'macro' thinking

A close-up of a star tunicate (Botryllus schlosseri): a filter feeding species found in marinas and harbours across South Africa. Credit: Luke Holman

Scientists at the University of Southampton have conducted a study that highlights the importance of studying a full range of organisms when measuring the impact of environmental change—from tiny bacteria, to mighty whales.

Researchers at the University's School of Ocean and Earth Science, working with colleagues at the universities of Bangor, Sydney and Johannesburg and the UK's National Oceanography Centre, undertook a survey of marine animals, protists (single cellular organisms) and bacteria along the coastline of South Africa.

Lead researcher and postgraduate student at the University of Southampton, Luke Holman explains: "Typically, biodiversity and biogeography studies focus on one group of species at a time, often animals. Studying animals, protist and bacteria together—organisms vastly different in size, separated by billions of years of evolution—gave us the opportunity to take a broader view of the marine ecosystem. We discovered remarkably consistent biogeographic groupings for the three across the coastline—consistent with previously studied patterns, driven by regional currents."

Findings are published in the journal Nature Ecology and Evolution.

The team took seawater samples in numerous locations along the length of the South African coast, from the warmer seas of the east, to the cooler waters of the west and the intermediate temperatures in the south. The samples were filtered, had environmental DNA extracted and underwent sophisticated lab analysis to indicate the diverse range of organisms found in particular locations.

Results showed a broad range of animals living in the sea along the whole length of coast, but with differences in the exact species in warm, cold and intermediate regions. This same pattern of difference was also shown in bacteria and protists—demonstrating consistency in the biodiversity of life for each region.

Furthermore, the scientists found that among the variables examined temperature had the greatest impact on determining the diversity of animals and bacteria, whereas protists were associated more with chlorophyll concentration in the water. The team also revealed that while all three groups were affected to some extent by human activity, such as shipping, fishing and building of marinas, this wasn't to the extent they'd expected.

Commenting on the study, Luke said: "We hope our work encourages researchers to consider other groups of organisms, both in biogeographic assessments and marine protection and restoration projects. For example, a project aiming to restore a coral reef might also need to consider the bacterial communities, or the protection of a river system might also ensure the protists communities are monitored in addition to the fish."

Moving forwards the team hope to learn more about the causes and consequences of global marine biodiversity change for all life, from microscopic bacteria and protists to macroscopic organisms like fish and marine mammals.


3 RESULTS

Throughout our search timeline, the use of “Anthropocene” in scientific literature has exponentially increased. Of those mentions, only a small portion were conservation-focused articles as the number of articles meeting the “Anthropocene & conservation” search criteria increased only gradually (Figure 1). In both cases, 2013 was the year where the acceleration in the use of the term “Anthropocene” began.

We gathered 77 articles that met our search criteria for Anthropocene literature. Of these, 45 (58.4%) conducted research in field locations in the Global North and 31 (40.3%) in the Global South. Of the 74 articles meeting our search criteria for conservation journals, 32 (43.2%) conducted research in field locations in the Global North, and 42 (56.8%) in the Global South. The majority of research in the Global South was being conducted in Central and South America. The conservation journals showed a similar pattern but with more representation in African countries (Table 1). There were no significant differences in the geographic areas where studies were taking place between Anthropocene and conservation biology papers (X 2 [DF 8, N = 73] = 1.6124, p = .80656). The list of 77 articles can be accessed and reused at https://digitalcommons.esf.edu/cgi/preview.cgi?article=1008&context=efb_fac.

Anthropocene Conservation
Central and South America 13 13
Pacific Islands 3 5
Asia 7 8
Africa 6 12
Middle East 0 1
Other 2 3
Total 31 42

The articles were published in a variety of journals Anthropocene articles were generated from 54 different journals with the Global North publishing in 47 different journals and the Global South publishing in 30 different journals. Overall, the distribution of Anthropocene articles was skewed with the top four journals producing 22% of the studies and 90% of the studies being published in 46 journals (Supporting Information Figure S1).

In order to explore if Anthropocene and conservation focused articles dealt with different key terms or organized themes along different topologies, we used VOSviewer to mine the titles and abstracts of the selected articles for the co-occurrence of terms for our two sets of articles. We set our threshold to five usages of the term, which initially generated 66 terms for the Anthropocene articles and 42 terms for the conservation articles. We reduced this by removing irrelevant terms such as “hypothesis”, “data”, and "i.e." that were commonly used but not directly relevant to the content of the papers, and “Anthropocene” and “conservation” because they were the original search terms (Bhattacharya & Basu, 1998 Lee, 2008 ). We generated a list of terms and linkages for each data set (Tables 2 and 3). We also generated term density maps using 54 terms for the Anthropocene articles and 35 terms for the conservation biology articles (Figure 2a,b). The two sets of articles showed different patterns of term usages and linkages.

Cluster 1 Cluster 2 Cluster 3
Animal Ability Climate
Case study Approach Climate change
Consequence Area Decade
Decline Biodiversity Distribution
Diversity Change Environment
Extinction Combination Future
Forest Ecosystem Habitat
Importance Ecosystem service Impact
Loss Factor Individual
Plant species Human Majority
Population Human activity Model
Process Increase Period
Proxy Land use Presence
Range Landscape Response
Richness Management Site
Seed dispersal Protected area Time
Species Region Year
Species richness Value
Taxa
Cluster 1 Cluster 2 Cluster 3 Cluster 4
Biodiversity Area Change Implication
Distribution Extinction Ecosystem Landscape
Diversity Interaction Growth Management
Elevation Plant Increase Population
Forest Presence Model Rate
Habitat Process Region
Impact Site Relationship
Importance Species Risk
Pattern Threat Time
Precipitation Year
Temperature

The Anthropocene articles had 1,177 links between terms and a total link strength of 3,459 (Table 2, Supporting Information Figure S2a). In this context, “links” represent co-occurrences between two keywords while strength of that link is a positive integer related to the frequency of those terms co-occurring across the literature. The sum of the strength indicates the interconnectivity within clusters (van Eck & Waltman, 2019 ). The higher this number the flatter the topic surface is, while low links can indicate “hills” within the topic topology resulting from insular key word clusters. The terms were grouped into three clusters by VOSviewer's “Network Visualization” function. Cluster 1 contained 19 terms, with “species” as the most connected one (53 links, total link strength of 430). As a whole, the cluster considered the study of species and populations. Cluster 2 contained 18 terms, with “change” as the most significant one (52 links, total link strength of 289). The cluster dealt with changes and conservation at the larger ecosystem and landscape-level scales. Cluster 3, the smallest of the clusters, contained “impact” as the most connected term with 52 links and a total link strength of 191. This cluster dealt primarily with predicting future changes.

The conservation biology articles had 506 links, for a total link strength of 1,645 (Table 3, Supporting Information Figure S2b). These terms were grouped into four distinct clusters by VOSviewer's “Network Visualization” function. Cluster 1 had 11 terms with “habitat” as its most-connected term, with 33 links and a total link strength of 146. Cluster 2 had 10 terms. “Species,” the most connected term, had 34 links and a total link strength of 250. Cluster 3 had 9 terms, with “region” as the most connected (33 links and a total link strength of 160). Cluster 4, the smallest grouping, contained only five terms, with “population” as the most connected 33 links and a total link strength of 126.

Unequal representation in authorship was apparent throughout both Anthropocene and conservation biology articles. Studies conducted in regions of the Global South were less likely to have a first (two-proportion z-test, p = .008) or last (two-proportion z-test, p < .001) author based in the country of the study compared to research conducted in the Global North (Table 4). The same representation pattern occurred in conservation biology articles (two-proportion z-test: First Author p = .002 Last Author p < .001 Table 4). Additionally, only 80.6% of articles conducted in Global South regions had any author based in the region on the paper which was significantly less than Global North regions with 95.5% of articles having an author based in the country of study (two-proportion z-test, p = .054). The same disparity occurred in conservation biology articles with 83.3% and 96.9% of papers having an author based in the region of study in Global South and Global North, respectively (two-proportion z-test, p = .038).

Anthropocene Conservation
Global North (n = 45) Global South (n = 31) Global North (n = 32) Global South (n = 42)
First author 0.844 0.548 0.906 0.619
p = .008 p = .002
Last author 0.867 0.467 0.875 0.524
p = .000 p = .000
Any author 0.956 0.806 0.969 0.833
p = .054 p = .038
  • Notes: p-Values indicate the significance of the difference in proportion between the Global North and the Global South for each author category.

There was no difference in the number of citations/year between the Global North and Global South within Anthropocene articles (p = .227 GN: = 2.50, s = 3.58 GS: = 1.72, s = 1.97). We explored two factors which may influence citation, impact factor as a proxy for local vs. international focused journals (Stocks et al., 2008 ) and number of coauthors (Abt, 2017 ). There was no difference in the mean impact factor between Anthropocene and conservation articles nor the Global North/Global South (Supporting Information Table S3). When exploring the relationship between authorship and impact factor, we found no relationship between the proportion of authors based in the Global South and the impact factor in which the article was published (Figure 3 Anthropocene: R 2 = 0.01, conservation: R 2 = 0.12). Lastly, there was no difference in the mean number of coauthors per paper between Anthropocene and conservation articles (p = .277 Anthropocene: = 5.18, s = 3.37 conservation: = 5.82, s = 3.85).

The coauthorship maps produced using the R package “refsplitr” showed different patterns of interconnections between Anthropocene and conservation papers (Figure 3). The conservation map shows a concentration of networks between Global North countries, particularly the United States and Europe. The distribution of nodes (institutions) is widespread, but most networks in the Global South lead to nodes in the Global North in the conservation maps. The Anthropocene map shows a greater distribution and strength of networks throughout the Global South and establishes connections between Global South countries, particularly South East Asia to South America. The connection between the United States and Europe is much weaker in the Anthropocene map, and the map adds numerous Global North locations like Alaska and northern Canada. The number of nodes stayed relatively the same between maps.


S.B.J. and R.S. planned and designed the research. S.B.J., F.V. and B.V. analyzed the data. I.V. provided material. S.B.J., R.S., E.D.L., F.V., E.S. and B.V. wrote the manuscript.

Please note: Wiley Blackwell are not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing material) should be directed to the New Phytologist Central Office.

Fig. S1 B east maximum clade credibility tree of Zingiberales.

Fig. S2 Bayesian consensus phylogram of plastid and nuclear dataset.

Fig. S3 B east phylogram of the combined plastid and nuclear dataset of Musaceae.

Table S1 Accession numbers, voucher data and origin of plant material for taxa included in the combined DNA analyses of Zingiberales–Musaceae

Table S2 Dispersal probabilities between the different Southeast Asian (and African) areas

Table S3 Sequence characteristics

Table S4 Model fit of area-dependent diversification

Methods S1 Taxon sampling.

Methods S2 Molecular protocols and sequence analyses.

Methods S3 B east detail methods, parameters and settings.

Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.