Browsing by Author "Herrera, JP"

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    Convergent evolution in lemur environmental niches
    (Journal of Biogeography, 2020-04-01) Herrera, JP
    Aim: To test the hypothesis that adaptive convergent evolution of climate niches occurred in multiple independent lemur lineages. Location: Madagascar. Taxon: Lemurs. Methods: I collected climate and altitude data from WorldClim and summarized the niches of almost all living lemurs (83 species) into phylogenetically controlled principal components. To test for convergent evolution, I searched for multiple, similar climate optima using multi-peak Ornstein–Uhlenbeck models (surface, l1-ou, bayou). I compared the observed level of climate convergence to that simulated under neutral and single-optimum models. To test if behavioural or morphological traits were related to climate niches, I used phylogenetic regressions with activity pattern, diet, and body size. Results: From an ancestral niche with high rainfall and low seasonality, four lemur lineages independently converged on climate niche optima characterized by high temperatures and low rainfall, supporting adaptive evolution in southwest deciduous and arid habitats. The observed level of convergence was more frequent than expected under Brownian motion and single-optimum simulations, which illustrates that the results are likely not a result of stochastic evolution over long time periods. Nocturnal and cathemeral activity patterns were common among lineages in the arid climate niche. Conclusion: Lemur climate niche evolution demonstrated that convergence explains the distribution of four independent clades in hot, arid environments of southwest Madagascar. The timing of these convergent shifts coincided with the origination of modern arid-adapted plant genera, some of which are important lemur food sources. These communities have high endemicity and are especially threatened by habitat loss. Arid environments are arenas in which convergent evolution is predicted to occur frequently.
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    Estimating the population size of lemurs based on their mutualistic food trees
    (Journal of Biogeography, 2018-11-01) Herrera, JP; Borgerson, C; Tongasoa, L; Andriamahazoarivosoa, P; Rasolofoniaina, BJR; Rakotondrafarasata, ER; Randrianasolo, JLRR; Johnson, SE; Wright, PC; Golden, CD
    Aim: Species’ distributions and abundances are primarily determined by the suitability of environmental conditions, including climate and interactions with sympatric species, but also increasingly by human activities. Modelling tools can help in assessing the extinction risk of affected species. By combining species distribution modelling of abiotic and biotic niches with population size modelling, we estimated the abundance of 19 lemur taxa in three regions, especially focusing on 10 species that are considered Endangered or Critically Endangered. Location: Madagascar. Taxa: Lemurs (Primates) and angiosperm trees. Methods: We used climate data, field samples, and published occurrence data on trees to construct species distribution models (SDM) for lemur food tree species. We then inferred the SDMs for lemurs based on the probability of occurrence of their food trees as well as climate. Finally, we used tree SDMs, topography, distance to the forest edge, and field estimates of lemur population density to predict lemur abundance in general linear models. Results: The SDMs of lemur food trees were stronger predictors of the occurrence of lemurs than climate. The predicted probability of presence of food trees, slope, elevation, and distance from the forest edge were significant correlates of lemur density. We found that sixteen species had minimum estimated abundances greater than 10,000 individuals over >1,000km2. Three lemur species are especially threatened, with less than 2,500 individuals predicted for Cheirogaleus sibreei, and heavy hunting pressure for the relatively small populations of Indri indri and Hapalemur occidentalis. Main conclusions: Biotic interactors were important variables in SDMs for lemurs, allowing refined estimates of ranges and abundances. This paper provides an analytical workflow that can be applied to other taxonomic groups to substantiate estimates of species’ vulnerability to extinction.
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    Prioritizing protected areas in Madagascar for lemur diversity using a multidimensional perspective
    (Biological Conservation, 2017-03-01) Herrera, JP
    Biodiversity is affected by anthropogenic activities, with a trend of decreasing species richness with habitat degradation. Decreasing species richness erodes evolutionary history and ecosystem function, but taxonomic, phylogenetic and functional diversity can have contrasting patterns. It is essential to measure these dimensions of biodiversity explicitly and assess how they are valued in prioritizing protected areas (PAs) to conserve diversity. Madagascar is a biodiversity hotspot, with high diversity and endemism coupled with heavy anthropogenic pressure. The endemic primates – lemurs – are the most endangered mammal taxon. A recent action plan prioritized PAs based on lemur species richness, weighted by endangerment. This scheme does not capture the evolutionary, functional, or biogeographic components of biodiversity, nor does it directly assess the level of human threat to those PAs. I compiled the largest dataset on lemur community composition in 100 PAs, including almost all lemur species (98 species). I combined data on lemur occurrence, their phylogeny, functional traits, IUCN Red List status, and environmental variables including deforestation between the years 2000 and 2014. I ranked PAs based on 14 metrics as well as the sum of metrics to determine how PA priorities compare under different valuation schemes. Based on the sum of seven metrics, I identified the top 25 PAs for lemur conservation. With these priority rankings, I propose areas of high lemur diversity, habitat heterogeneity and productivity, and deforestation be the focus of future conservation activities to maximize community resilience and prevent the erosion of evolutionary diversity and ecosystem function.
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    The Effects of Biogeography and Biotic Interactions on Lemur Community Assembly
    (International Journal of Primatology, 2017-08-01) Herrera, JP
    Geographic patterns of biodiversity result from broad-scale biogeographic and present-day ecological processes. The aim of this study was to investigate the relative importance of biogeographic history and ecology driving patterns of diversity in modern primate communities in Madagascar. I collected data on endemic lemur species co-occurrence from range maps and survey literature for 100 communities in protected areas. I quantified and compared taxonomic, phylogenetic, and functional dimensions of intra- and intersite diversity. I tested environmental and geographic predictors of diversity and endemism. I calculated deforestation rates within protected areas between the years 2000 and 2014, and tested if diversity is related to forest cover and loss. I found the phylogenetic structure of lemur communities could be explained primarily by remotely sensed plant productivity, supporting the hypothesis that there was ecological differentiation among ecoregions, while functional-trait disparity was not strongly related to environment. Taxonomic and phylogenetic diversity also increased with increasing topographic heterogeneity. Beta diversity was explained by both differences in ecology among localities and potential river barriers. Approximately 3000 km2 were deforested in protected areas since the year 2000, threatening the most diverse communities (up to 31%/park). The strong positive association of plant productivity and topographic heterogeneity with lemur diversity indicates that high productivity, rugged landscapes support greater diversity. Both ecology and river barriers influenced lemur community ecology and biogeography. These results underscore the need for focused conservation efforts to slow the loss of irreplaceable evolutionary and ecological diversity.