• A diversity of biogeographies in an extreme Amazonian wetland habitat

      Householder, Ethan; Janovec, John; Tobler, Mathias W.; Wittmann, Florian; Myster, Randall W. (John Wiley & Sons, Ltd, 2017)
      Amazonian wetlands are associated with lower species diversity relative to surrounding terra firme forests, as well as compositional turnover along strong hydro-edaphic gradients. Because species differ in their ecophysiological response to soil waterlogging, hydrological regime is likely a major determinant of the local diversity, species distribution and assemblage of plant communities in wetland habitats....
    • A molecular phylogeny of the Pacific clade of Cyrtandra (Gesneriaceae) reveals a Fijian origin, recent diversification, and the importance of founder events

      Johnson, Melissa A.; Clark, John R.; Wagner, Warren L.; McDade, Lucinda A. (2017)
      Cyrtandra (Gesneriaceae) is among the largest genera of flowering plants in the remote oceanic islands of the Pacific, with an estimated 175 species distributed across an area that extends from the Solomon Islands, east to the Marquesas Islands, and north to the Hawaiian Islands. The vast majority of species are single-island endemics that inhabit upland rainforests....
    • Contrasting patterns of movement across life stages in an insular iguana population

      Moss, Jeanette B.; Gerber, Glenn P.; Goetz, Matthias; Haakonsson, Jane E.; Harvey, Jessica C.; Laaser, Tanja; Welch, Mark E. (2020)
    • Data gaps and opportunities for comparative and conservation biology

      Conde, Dalia A.; Staerk, Johanna; Colchero, Fernando; da Silva, Rita; Schöley, Jonas; Baden, H. Maria; Jouvet, Lionel; Fa, John E.; Syed, Hassan; Jongejans, Eelke; et al. (2019)
      Biodiversity loss is a major challenge. Over the past century, the average rate of vertebrate extinction has been about 100-fold higher than the estimated background rate and population declines continue to increase globally. Birth and death rates determine the pace of population increase or decline, thus driving the expansion or extinction of a species. Design of species conservation policies hence depends on demographic data (e.g., for extinction risk assessments or estimation of harvesting quotas). However, an overview of the accessible data, even for better known taxa, is lacking. Here, we present the Demographic Species Knowledge Index, which classifies the available information for 32,144 (97%) of extant described mammals, birds, reptiles, and amphibians. We show that only 1.3% of the tetrapod species have comprehensive information on birth and death rates. We found no demographic measures, not even crude ones such as maximum life span or typical litter/clutch size, for 65% of threatened tetrapods. More field studies are needed; however, some progress can be made by digitalizing existing knowledge, by imputing data from related species with similar life histories, and by using information from captive populations. We show that data from zoos and aquariums in the Species360 network can significantly improve knowledge for an almost eightfold gain. Assessing the landscape of limited demographic knowledge is essential to prioritize ways to fill data gaps. Such information is urgently needed to implement management strategies to conserve at-risk taxa and to discover new unifying concepts and evolutionary relationships across thousands of tetrapod species.
    • Devastating decline of forest elephants in Central Africa

      Maisels, F.; Strindberg, S.; Blake, S.; Wittemyer, G.; Hart, J.; Williamson, E. A.; Aba'a, R.; Abitsi, G.; Ambahe, R. D.; Amsini, F.; et al. (2013)
      African forest elephants-taxonomically and functionally unique-are being poached at accelerating rates, but we lack range-wide information on the repercussions. Analysis of the largest survey dataset ever assembled for forest elephants (80 foot-surveys; covering 13,000 km; 91,600 person-days of fieldwork) revealed that population size declined by ca. 62% between 2002-2011, and the taxon lost 30% of its geographical range. The population is now less than 10% of its potential size, occupying less than 25% of its potential range. High human population density, hunting intensity, absence of law enforcement, poor governance, and proximity to expanding infrastructure are the strongest predictors of decline. To save the remaining African forest elephants, illegal poaching for ivory and encroachment into core elephant habitat must be stopped. In addition, the international demand for ivory, which fuels illegal trade, must be dramatically reduced.
    • Genomic comparisons reveal biogeographic and anthropogenic impacts in the koala ( Phascolarctos cinereus ): a dietary-specialist species distributed across heterogeneous environments

      Kjeldsen, Shannon R.; Raadsma, Herman W.; Leigh, Kellie A.; Tobey, Jennifer R.; Phalen, David; Krockenberger, Andrew; Ellis, William A.; Hynes, Emily; Higgins, Damien P.; Zenger, Kyall R. (2018)
      The Australian koala is an iconic marsupial with highly specific dietary requirements distributed across heterogeneous environments, over a large geographic range. The distribution and genetic structure of koala populations has been heavily influenced by human actions, specifically habitat modification, hunting and translocation of koalas. There is currently limited information on population diversity and gene flow at a species-wide scale, or with consideration to the potential impacts of local adaptation. Using species-wide sampling across heterogeneous environments, and high-density genome-wide markers (SNPs and PAVs), we show that most koala populations display levels of diversity comparable to other outbred species, except for those populations impacted by population reductions. Genetic clustering analysis and phylogenetic reconstruction reveals a lack of support for current taxonomic classification of three koala subspecies, with only a single evolutionary significant unit supported. Furthermore, ~70% of genetic variance is accounted for at the individual level. The Sydney Basin region is highlighted as a unique reservoir of genetic diversity, having higher diversity levels (i.e., Blue Mountains region; AvHecorr=0.20, PL%?=?68.6). Broad-scale population differentiation is primarily driven by an isolation by distance genetic structure model (49% of genetic variance), with clinal local adaptation corresponding to habitat bioregions. Signatures of selection were detected between bioregions, with no single region returning evidence of strong selection. The results of this study show that although the koala is widely considered to be a dietary-specialist species, this apparent specialisation has not limited the koala’s ability to maintain gene flow and adapt across divergent environments as long as the required food source is available.
    • Incorporating mortality into habitat selection to identify secure and risky habitats for savannah elephants

      Roever, C. L.; van Aarde, R. J.; Chase, Michael J. (2013)
      Empirical models of habitat selection are increasingly used to guide and inform habitat-based management plans for wildlife species. However, habitat selection does not necessarily equate to habitat quality particularly if selection is maladaptive, so incorporating measures of fitness into estimations of occurrence is necessary to increase model robustness. Here, we incorporated spatially explicit mortality events with the habitat selection of elephants to predict secure and risky habitats in northern Botswana....
    • Low levels of fruit nitrogen as drivers for the evolution of Madagascar’s primate communities

      Donati, Giuseppe; Santini, Luca; Eppley, Timothy M.; Arrigo-Nelson, Summer J.; Balestri, Michela; Boinski, Sue; Bollen, An; Bridgeman, LeAndra L.; Campera, Marco; Carrai, Valentina; et al. (2017)
      The uneven representation of frugivorous mammals and birds across tropical regions – high in the New World, low in Madagascar and intermediate in Africa and Asia – represents a long-standing enigma in ecology. Several hypotheses have been proposed to explain these differences but the ultimate drivers remain unclear. Here, we tested the hypothesis that fruits in Madagascar contain insufficient nitrogen to meet primate metabolic requirements, thus constraining the evolution of frugivory. We performed a global analysis of nitrogen in fruits consumed by primates, as collated from 79 studies. Our results showed that average frugivory among lemur communities was lower compared to New World and Asian-African primate communities. Fruits in Madagascar contain lower average nitrogen than those in the New World and Old World. Nitrogen content in the overall diets of primate species did not differ significantly between major taxonomic radiations. There is no relationship between fruit protein and the degree of frugivory among primates either globally or within regions, with the exception of Madagascar. This suggests that low protein availability in fruits influences current lemur communities to select for protein from other sources, whereas in the New World and Old World other factors are more significant in shaping primate communities.
    • Low MHC variation in the polar bear: Implications in the face of Arctic warming?

      Weber, D.S.; Van Coeverden de Groot, P.J.; Schrenzel, Mark D.; Perez, D.A.; Thomas, S. (2013)
      Animals in the Arctic have low pathogen diversity but with rapid climate warming, this is expected to change. One insidious consequence of climate change is exposure of Arctic species to new pathogens derived from more southern species expanding their range northward. To assess potential vulnerability of polar bears to disease exposure, we examined genetic variation in major histocompatibility complex (MHC) loci (part of immune system) in Canadian polar bears and found low genetic diversity, consistent with long?standing exposure to low pathogen/parasite loads....
    • Montane bias in lowland Amazonian peatlands: Plant assembly on heterogeneous landscapes and potential significance to palynological inference

      Householder, J. E.; Wittmann, F.; Tobler, Mathias W.; Janovec, J. P. (2015)
      Past temperature changes in tropical mountain regions are commonly inferred from vertical elevational shifts of montane indicator taxa in the palynological record.…To the extent that fossilization provides a better record of past vegetation that occurred proximate to the site of deposition, we suggest that habitat tracking of montane elements may introduce a cool bias in lowland paleo-temperature reconstructions based on pollen proxies.
    • Sumatran tiger survival threatened by deforestation despite increasing densities in parks

      Luskin, Matthew Scott; Albert, Wido Rizki; Tobler, Mathias W. (2017)
      The continuing development of improved capture–recapture (CR) modeling techniques used to study apex predators has also limited robust temporal and cross-site analyses due to different methods employed. We develop an approach to standardize older non-spatial CR and newer spatial CR density estimates and examine trends for critically endangered Sumatran tigers (Panthera tigris sumatrae) using a meta-regression of 17 existing densities and new estimates from our own fieldwork. We find that tiger densities were 47% higher in primary versus degraded forests and, unexpectedly, increased 4.9% per yr from 1996 to 2014, likely indicating a recovery from earlier poaching. However, while tiger numbers may have temporarily risen, the total potential island-wide population declined by 16.6% from 2000 to 2012 due to forest loss and degradation and subpopulations are significantly more fragmented. Thus, despite increasing densities in smaller parks, we conclude that there are only two robust populations left with >30 breeding females, indicating Sumatran tigers still face a high risk of extinction unless deforestation can be controlled.