The metabolic theory of ecology convincingly explains the latitudinal diversity gradient of Neotropical freshwater fish

AbstractAimThe evolutionary causes of the latitudinal diversity gradient are debated. Hypotheses have ultimately invoked either faster rates of diversification in the tropics, or more time for diversification due to the tropical origins of higher taxa. Here we perform the first test of the diversification rate and time hypotheses in freshwater ray-finned fishes, a group comprising nearly a quarter of all living vertebrates.LocationGlobal.Time period368–0 mya.Major taxa studiedExtant freshwater ray-finned fishes.MethodsUsing a mega-phylogeny of actinopterygian fishes and a global database of occurrence records, we estimated net diversification rates, the number of colonizations and regional colonization times of co-occurring species in freshwater drainage basins. We used Generalized Additive Models to test whether these factors were related to latitude. We then compared the influence of diversification rates, colonization numbers, colonization times and surface area on species richness, and how these factors are related to each other.ResultsWhile both diversification rates and time were related to richness, time had greater explanatory power and was more strongly related to latitude than diversification rates. Other factors (basin surface area, number of colonizations) also helped explain richness but were unrelated to latitude. The world’s most diverse freshwater basins (Amazon, Congo rivers) were dominated by lineages with Mesozoic origins. The temperate groups dominant today arrived near the K-Pg boundary, leaving comparatively less time to build richness. Diversification rates and colonization times were inversely related: recently colonized basins had the fastest rates, while ancient species-rich faunas had slower rates.Main conclusionsWe concluded that time is the lead driver of latitudinal richness disparities in freshwater fish faunas. We suggest that the most likely path to building very high species richness is through diversification over long periods of time, rather than diversifying quickly.

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Exploring the origin of the latitudinal diversity gradient: Contrasting the sister fern generaPhegopterisandPseudophegopteris

Journal of Systematics and Evolution ◽

10.1002/jse.234 ◽

2012 ◽

pp. n/a-n/a

Author(s):

Harald SCHNEIDER ◽

Li-Juan HE ◽

Jeannine MARQUARDT ◽

Li WANG ◽

Jochen HEINRICHS ◽

...

Keyword(s):

Latitudinal Diversity Gradient ◽

Diversity Gradient

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Inferring ecological processes underlying the latitudinal diversity gradient in New World swallowtail butterflies (Papilio, Heraclides, andPterourus)

10.1603/ice.2016.109466 ◽

2016 ◽

Author(s):

Hannah L Owens

Keyword(s):

New World ◽

Ecological Processes ◽

Latitudinal Diversity Gradient ◽

Diversity Gradient ◽

Swallowtail Butterflies

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The Metabolic Theory of Ecology

10.1093/oso/9780199551668.003.0012 ◽

2017 ◽

Author(s):

Andrew Clarke

Keyword(s):

Metabolic Rate ◽

Resting Metabolic Rate ◽

Effect Of Temperature ◽

Thermal Ecology ◽

Model Data ◽

Metabolic Theory ◽

Physical Explanation ◽

Boltzmann Factor ◽

Scaling Exponents ◽

Metabolic Theory Of Ecology

The model of West, Brown & Enquist (WBE) is built on the assumption that the metabolic rate of cells is determined by the architecture of the vascular network that supplies them with oxygen and nutrients. For a fractal-like network, and assuming that evolution has minimised cardiovascular costs, the WBE model predicts that s=metabolism should scale with mass with an exponent, b, of 0.75 at infinite size, and ~ 0.8 at realistic larger sizes. Scaling exponents ~ 0.75 for standard or resting metabolic rate are observed widely, but far from universally, including in some invertebrates with cardiovascular systems very different from that assumed in the WBE model. Data for field metabolic rate in vertebrates typically exhibit b ~ 0.8, which matches the WBE prediction. Addition of a simple Boltzmann factor to capture the effects of body temperature on metabolic rate yields the central equation of the Metabolic Theory of Ecology (MTE). The MTE has become an important strand in ecology, and the WBE model is the most widely accepted physical explanation for the scaling of metabolic rate with body mass. Capturing the effect of temperature through a Boltzmann factor is a useful statistical description but too simple to qualify as a complete physical theory of thermal ecology.

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