Latitudinal difference in biodiversity caused by higher tropical rate of increase

Buzas, Martin A.; Collins, Laurel S.; Culver, Stephen J.

doi:10.1073/pnas.122241499

Cited by 106 publications

(73 citation statements)

References 23 publications

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“…This general pattern is most notably expressed in the latitudinal gradient of species richness that typically sees much greater tropical diversity relative to cooler habitats (26). Support for this concept also comes from evidence in fossil records where consistently greater rates of tropical speciation over geological time have been found (27). Correspondingly, the latitudinal location of the first appearance in fossil records of apomorphic characters favors the tropics, with poleward deflections observed for the occurrence of plesiomorphic life forms (28)(29)(30)(31).…”

Section: Resultsmentioning

confidence: 92%

The road from Santa Rosalia: A faster tempo of evolution in tropical climates

Wright

Keeling

Gillman

2006

Proc. Natl. Acad. Sci. U.S.A.

207

221

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Using an appropriately designed and replicated study of a latitudinal influence on rates of evolution, we test the prediction by K. Rohde [(1992) Oikos 65, 514 -527] that the tempo of molecular evolution in the tropics is greater than at higher latitudes. Consistent with this prediction we found tropical plant species had more than twice the rate of molecular evolution as closely related temperate congeners. Rohde's climate-speciation hypothesis constitutes one explanation for the cause of that relationship. This hypothesis suggests that mutagenesis occurs more frequently as productivity and metabolic rates increase toward the equator. More rapid mutagenesis was then proposed as the mechanism that increases evolutionary tempo and rates of speciation. A second possible explanation is that faster rates of molecular evolution result from higher tropical speciation rates However, we targeted common species to limit the influence of genetic drift, and many of the tropical species we used, despite occurring in abundant populations, had much higher rates of molecular evolution. Nonetheless, this issue is not completely resolved by that precaution and requires further examination.latitude ͉ metabolic rate ͉ molecular evolution ͉ mutagenesis ͉ speciation T he decrease in species richness along the continuum from tropical to polar latitudes is perhaps one of the most widely recognized patterns in nature, yet there is no consensus as to a causal mechanism (1, 2). Indeed, since Hutchinson (3) explored a range of possibilities in his 1959 address, ''homage to Santa Rosalia or why are there so many kinds of animals?'', a plethora of competing ideas that attempt to explain the pattern have emerged (4, 5). In 1808, von Humboldt (6) first suggested that energy was key in generating this relationship, and there are now several theories invoking energy as a determinant of diversity (5). These include the climate-speciation hypothesis of Rohde (7). The central element of that hypothesis is the idea that in warmer, more productive environments metabolic rates are higher and that because the rate of mutagenesis is thought to be positively correlated with metabolic rate (8) the tempo of both evolution and speciation is also greater (7). If rate heterogeneity in molecular evolution is controlled by climate it would also suggest that evolution is a spatially ordered phenomenon as was first proposed by Darwin (9). Here, we test the prediction made by Rhode (7) that rates of molecular evolution are faster in the tropics than at higher latitudes. Alternative hypotheses that might also explain faster molecular evolution in the tropics include: first, the concept under nearly neutral theory that faster rates of genetic drift occur in generally smaller tropical populations (10, 11), and second, the concept of more rapid tropical speciation rates themselves produce faster rates of molecular evolution at low latitudes (12).Nucleotide substitution rates have been found to correlate positively with body temperature where phylogenetically disparat...

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Section: Resultsmentioning

confidence: 92%

The road from Santa Rosalia: A faster tempo of evolution in tropical climates

Wright

Keeling

Gillman

2006

Proc. Natl. Acad. Sci. U.S.A.

207

221

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“…In addition, there are evidences of the relation between increase in plant species richness with decrease of latitudinal gradient (Signor 1990;Cox and Moore 2010). This relationship is widely accepted, based on various theories: temporal, spatial, competitive, predictive, climate stability and biological production (Blackburn and Gaston 1996;Buzas et al 2002;Raven et al 2007). Therefore, the bioclimatic features related to the low latitude of Northern Brazil can also explain the high richness of aquatic macrophytes in this region.…”

Section: Discussionmentioning

confidence: 99%

Updated checklist of aquatic macrophytes from Northern Brazil

et al. 2015

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Field collection and herbaria data did not allow to quantify the diversity of aquatic plants from Northern Brazil, so we could not detect biogeographic patterns. Therefore, our objectives were to identify and quantify the aquatic macrophytes of North Brazilian states, analyzing herbaria data plataforms (SpeciesLink and Flora do Brasil). The checklist was produced by bibliographic search (articles published between 1980 and 2000), herbaria collections of the platforms SpeciesLink and Flora do Brasil and field expeditions, where we utilized asystematic sampling. We also analyzed the floristic similarity of aquatic macrophytes among Northern Brazil, wetlands of distinct Brazilian regions and the Neotropics. We recorded 539 species, of which 48 are endemic to Brazil. The states with highest number of species were Amazonas and Pará, independently on platform. The most represented families were Poaceae (89 species), Podostemaceae (55), Cyperaceae (50) and Fabaceae (47). We highlight the unprecedent richness of Podostemaceae, due to our own field collection efforts on favorable habitats, 25 species being endemic. Emergent and/or amphibious plants (515) were dominant in total species richness and were best represented in lotic habitats. We found significant differences in richness and floristics among states, obtained from the platforms. There is floristic similarity among Northern states and other Brazilian wetlands. In conclusion, we observed a rich aquatic flora in Northern Brazil, in spite of scarcity of records for Acre, Rondonia and Tocantins; we highlight the unprecedent number of endemic species of Podostemaceae (25) and contrasting richness between SpeciesLink and Flora do Brasil. KEYWORDS: floristics, life forms, Podostemaceae, species richness Lista atualizada de macrófitas aquáticas da região Norte do Brasil RESUMOOs eforços de campo e os dados de herbários não nos permitiam quantificar a diversidade plantas aquáticas no Norte do Brasil e, com isso, nos impediam de traçar padrõres biogeográficos sobre essa comunidade. Assim, o presente estudo teve por objetivos identificar e quantificar as macrófitas aquáticas dos estados do Norte do Brasil, analisando duas plataformas de dados de herbarios (SpeciesLink e Flora do Brasil). O checklist baseou-se em levantamento bibliográfico (revistas e artigos publicados entre 1980 e 2000) e em coletas de campo, na qual foi utilizada amostragem de "caminhamento". Após a elaboração do checklist, verificaram-se os registros das espécies para os estados da região, consultando-se as coleções das plataformas SpeciesLink e Flora do Brasil. Foi analisada a similaridade de especies de macrófitas aquáticas do Neotrópico, Norte do Brasil e ecossistemas aquáticos de distintas regiões do país. Foram registradas 539 espécies, sendo 48 endêmicas do Brasil. As famílias mais representativas foram Poaceae (89 espécies), Podostemaceae (55), Cyperaceae (50) e Fabaceae (47). Ressaltamos a inédita riqueza de Podostemaceae, devida a nossos esforços de coleta em ambientes propícios, 25 esp...

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“…Speciation rates recorded in the foramaniferan fossil record do, however, appear to increase with energy (Buzas & Culver, 1999 ;Buzas, Collins & Culver, 2002). The unified neutral theory of biodiversity (Hubbell, 2001), proposes that ' the number of new species arising per unit time is a function of the total number of individuals in a metacommunity '.…”

Section: (B ) Predictionsmentioning

confidence: 99%

Species–energy relationships at the macroecological scale: a review of the mechanisms

2005

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Correlations between the amount of energy received by an assemblage and the number of species that it contains are very general, and at the macro-scale such species-energy relationships typically follow a monotonically increasing curve. Whilst the ecological literature contains frequent reports of such relationships, debate on their causal mechanisms is limited and typically focuses on the role of energy availability in controlling the number of individuals in an assemblage. Assemblages from high-energy areas may contain more individuals enabling species to maintain larger, more viable populations, whose lower extinction risk elevates species richness. Other mechanisms have, however, also been suggested. Here we identify and clarify nine principal mechanisms that may generate positive species-energy relationships at the macro-scale. We critically assess their assumptions and applicability over a range of spatial scales, derive predictions for each and assess the evidence that supports or refutes them. Our synthesis demonstrates that all mechanisms share at least one of their predictions with an alternative mechanism. Some previous studies of species-energy relationships appear not to have recognised the extent of shared predictions, and this may detract from their contribution to the debate on causal mechanisms. The combination of predictions and assumptions made by each mechanism is, however, unique, suggesting that, in principle, conclusive tests are possible. Sufficient testing of all mechanisms has yet to be conducted, and no single mechanism currently has unequivocal support. Each may contribute to species-energy relationships in some circumstances, but some mechanisms are unlikely to act simultaneously. Moreover, a limited number appear particularly likely to contribute frequently to species-energy relationships at the macro-scale. The increased population size, niche position and diversification rate mechanisms are particularly noteworthy in this context.

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Latitudinal difference in biodiversity caused by higher tropical rate of increase

Cited by 106 publications

References 23 publications

The road from Santa Rosalia: A faster tempo of evolution in tropical climates

The road from Santa Rosalia: A faster tempo of evolution in tropical climates

Updated checklist of aquatic macrophytes from Northern Brazil

Species–energy relationships at the macroecological scale: a review of the mechanisms

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