Tropical mountain cradles of dry forest diversity

Dick, Christopher W.; Wright, S. Joseph

doi:10.1073/pnas.0505013102

Cited by 20 publications

(25 citation statements)

References 14 publications

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“…The origin of C. alliodora ant symbionts occurred approximately 15.4 Ma, which approximately corresponds to mid‐Miocene‐cooling scenarios for the expansion of tropical dry forests (Dick & Wright 2005; Graham 2010; De‐Nova et al. 2012).…”

Section: Discussionmentioning

confidence: 88%

Diversification and phylogeographic structure in widespread Azteca plant‐ants from the northern Neotropics

et al. 2012

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The Neotropical myrmecophytic tree Cordia alliodora hosts symbiotic Azteca ants in most of its widespread range. The taxonomy of the genus Azteca is notoriously difficult, which has frequently obscured species identity in ecological studies. We used sequence data from one mitochondrial and four nuclear loci to infer phylogenetic relationships, patterns of geographic distribution, and timing of diversification for 182 colonies of five C. alliodora-dwelling Azteca species from Mexico to Colombia. All morphological species were recovered as monophyletic, but we identified at least five distinct genetic lineages within the most abundant and specialized species, Azteca pittieri. Mitochondrial and nuclear data were concordant at the species level, but not within species. Divergence time analyses estimated that C. alliodora-dwelling Azteca shared a common ancestor approximately 10-22million years ago, prior to the proposed arrival of the host tree in Middle America. Diversification in A. pittieri occurred in the Pleistocene and was not correlated with geographic distance, which suggests limited historical gene flow among geographically restricted populations. This contrasts with the previously reported lack of phylogeographic structure at this spatial scale in the host tree. Climatic niches, and particularly precipitation-related variables, did not overlap between the sites occupied by northern and southern lineages of A. pittieri. Together, these results suggest that restricted gene flow among ant populations may facilitate local adaptation to environmental heterogeneity. Differences in population structure between the ants and their host trees may profoundly affect the evolutionary dynamics of this widespread ant-plant mutualism.

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Section: Discussionmentioning

confidence: 88%

Diversification and phylogeographic structure in widespread Azteca plant‐ants from the northern Neotropics

et al. 2012

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“…The same study posited that the limited range of these endemics could be due to recent speciation events, and that the species in question have not had enough time to fill their entire potential range. While it is not clear when the Mexican TDF hit its acme of speciation (see Dick & Wright, 2005), it is certainly possible that some of the endemics found there are still expanding their range.…”

Section: Discussionmentioning

confidence: 99%

Tropical dry forest trees and the relationship between local abundance and geographic range

Williams

Viers²,

Schwartz³

2010

Journal of Biogeography

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Aim To test the macroecological principle that a positive relationship exists between local abundance and geographic range size for tree communities in the tropical dry forest. Location Two tropical dry forest (TDF) regions on the Pacific coast of Mexico: one near Chamela, Jalisco; the other near Huatulco, Oaxaca. Methods We recorded species presence and relative abundance of trees and lianas from over 40 locales in each of the study regions using transects across an elevational gradient. We then compared the field data with occurrence data from national and online databases to examine how local patterns of abundance relate to putative geographic range areas and latitudinal breadth. Results We found no significant correlation between abundance and range size. Overall, many more locally abundant species had small ranges than large ones. We found that most species occupy the majority of the TDF range north of Colombia, and those species present in South America occupy the majority of that continent’s TDF range as well. This pattern was independent of local abundance. We also found no relationship between range size and local niche breadth as measured by elevation, or between local abundance and distance to the range centre. Main conclusions The macroecological tenet that posits a positive correlation between local abundance and geographic range size does not appear to hold for TDF trees. The finding that many locally abundant species had narrow ranges also suggests that dry forest endemics may be particularly well adapted to local conditions and make important contributions to community structure. We hypothesize that the absence of abundant species with large ranges is due to opposing environmental constraints that prevent a species from thriving everywhere.

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“…Our results highlight the potential vulnerability of ecosystems in relatively drier areas (i.e., northern part of the region) and their importance as a source of genes and species that could help ecosystems shifting to drier types-for example, the Mexican dry forests (Dick and Wright 2005). This could mean that changes in the network of protected areas and biological corridors of the Mesoamerican Biological Corridor (MBC) are needed, as it has been suggested for Canada's national park system (Scott et al 2002).…”

Section: Future Workmentioning

confidence: 97%

Modeling Potential Equilibrium States of Vegetation and Terrestrial Water Cycle of Mesoamerica under Climate Change Scenarios*

Imbach

Molina

Locatelli

et al. 2012

Journal of Hydrometeorology

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The likelihood and magnitude of the impacts of climate change on potential vegetation and the water cycle in Mesoamerica is evaluated. Mesoamerica is a global biodiversity hotspot with highly diverse topographic and climatic conditions and is among the tropical regions with the highest expected changes in precipitation and temperature under future climate scenarios. The biogeographic soil-vegetation-atmosphere model Mapped Atmosphere Plant Soil System (MAPSS) was used for simulating the integrated changes in leaf area index (LAI), vegetation types (grass, shrubs, and trees), evapotranspiration, and runoff at the end of the twenty-first century. Uncertainty was estimated as the likelihood of changes in vegetation and water cycle under three ensembles of model runs, one for each of the groups of greenhouse gas emission scenarios (low, intermediate, and high emissions), for a total of 136 runs generated with 23 general circulation models (GCMs). LAI is likely to decrease over 77%-89% of the region, depending on climate scenario groups, showing that potential vegetation will likely shift from humid to dry types. Accounting for potential effects of CO 2 on water use efficiency significantly decreased impacts on LAI. Runoff will decrease across the region even in areas where precipitation increases (even under increased water use efficiency), as temperature change will increase evapotranspiration. Higher emission scenarios show lower uncertainty (higher likelihood) in modeled impacts. Although the projection spread is high for future precipitation, the impacts of climate change on vegetation and water cycle are predicted with relatively low uncertainty.

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Tropical mountain cradles of dry forest diversity

Cited by 20 publications

References 14 publications

Diversification and phylogeographic structure in widespread Azteca plant‐ants from the northern Neotropics

Diversification and phylogeographic structure in widespread Azteca plant‐ants from the northern Neotropics

Tropical dry forest trees and the relationship between local abundance and geographic range

Modeling Potential Equilibrium States of Vegetation and Terrestrial Water Cycle of Mesoamerica under Climate Change Scenarios*

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