The historical biogeography of Mammalia

348

430

Documenting and exploring the patterns of diversity of life on Earth has always been a central theme in biology. Species richness despite being the most commonly used measure of diversity in macroecological studies suffers from not considering the evolutionary and ecological differences among species. Phylogenetic diversity (PD) and functional diversity (FD) have been proposed as alternative measures to overcome this limitation. Although species richness, PD and FD are closely related, their relationships have never been investigated on a global scale. Comparing PD and FD with species richness corroborated the general assumptions of surrogacy of the different diversity measures. However, the analysis of the residual variance suggested that the mismatches between the diversity measures are influenced by environmental conditions. PD increased relative to species richness with increasing mean annual temperature, whereas FD decreased with decreasing seasonality relative to PD. We also show that the tropical areas are characterized by a FD deficit, a phenomenon, that suggests that in tropical areas more species can be packed into the ecological space. We discuss potential mechanisms that could have resulted in the gradient of spatial mismatch observed in the different biodiversity measures and draw parallels to local scale studies. We conclude that the use of multiple diversity measures on a global scale can help to elucidate the relative importance of historical and ecological processes shaping the present gradients in mammalian diversity.

Section: Discussionmentioning

confidence: 99%

Understanding global patterns of mammalian functional and phylogenetic diversity

Safi

Cianciaruso

Loyola

et al. 2011

348

430

“…If biogeographic history has been important in shaping mammalian diversity [52], then it should be considered alongside ecological or life-history differences when trying to understand clade-richness patterns [53]. It may also explain why ecological or life-history differences alone have so far explained little of the variance in species-richness among mammalian clades in phylogenetic comparative analyses.…”

Section: Winners and Losers: Pinpointing Shifts In Diversification Ratementioning

confidence: 99%

The shape of mammalian phylogeny: patterns, processes and scales

Purvis

Fritz

Rodrı́guez

et al. 2011

Mammalian phylogeny is far too asymmetric for all contemporaneous lineages to have had equal chances of diversifying. We consider this asymmetry or imbalance from four perspectives. First, we infer a minimal set of 'regime changes'-points at which net diversification rate has changedidentifying 15 significant radiations and 12 clades that may be 'downshifts'. We next show that mammalian phylogeny is similar in shape to a large set of published phylogenies of other vertebrate, arthropod and plant groups, suggesting that many clades may diversify under a largely shared set of 'rules'. Third, we simulate six simple macroevolutionary models, showing that those where speciation slows down as geographical or niche space is filled, produce more realistic phylogenies than do models involving key innovations. Lastly, an analysis of the spatial scaling of imbalance shows that the phylogeny of species within an assemblage, ecoregion or larger area always tends to be more unbalanced than expected from the phylogeny of species at the next more inclusive spatial scale. We conclude with a verbal model of mammalian macroevolution, which emphasizes the importance to diversification of accessing new regions of geographical or niche space.

“…through competition or predation). At a global scale, it is clear that evolutionary biogeography places strong constraints on regional abundance and species richness [41,42], but it is not clear whether this kind of nonindependence translates into the statistical independence assumed by McGill [8].…”

Section: (D) Species Abundance Distributionmentioning

confidence: 99%

“…(c) Temporal patterns in biodiversity Diversification rates across mammals have not been equal [41,98], which has led to significant imbalance in the distribution of species at nodes in the mammalian phylogenetic tree over time. This diversification rate variation leads to the distribution of species among higher taxa following a hollow curve, i.e.…”

Section: Other Mammalian Biodiversity Patternsmentioning

confidence: 99%

Can unified theories of biodiversity explain mammalian macroecological patterns?

Jones

Blackburn

Isaac

2011

The idea of a unifying theory of biodiversity linking the diverse array of macroecological patterns into a common theoretical framework is very appealing. We explore this idea to examine currently proposed unified theories of biodiversity (UTBs) and their predictions. Synthesizing the literature on the macroecological patterns of mammals, we critically evaluate the evidence to support these theories. We find general qualitative support for the UTBs' predictions within mammals, but rigorous testing is hampered by the types of data typically collected in studies of mammals. In particular, abundance is rarely estimated for entire mammalian communities or of individual species in multiple locations, reflecting the logistical challenges of studying wild mammal populations. By contrast, there are numerous macroecological patterns (especially allometric scaling relationships) that are extremely well characterized for mammals, but which fall outside the scope of current UTBs. We consider how these theories might be extended to explain mammalian biodiversity patterns more generally. Specifically, we suggest that UTBs need to incorporate the dimensions of geographical space, species' traits and time to reconcile theory with pattern.