Latitudinal gradients in species diversity

Map latitudinal gradient of living terrestrial vertebrate species richness (Mannion 2014)

Species richness, or biodiversity, increases from the poles to the tropics for a wide variety of terrestrial and marine organisms, often referred to as the latitudinal diversity gradient.[1] The latitudinal diversity gradient is one of the most widely recognized patterns in ecology.[1] It has been observed to varying degrees in Earth's past.[2] A parallel trend has been found with elevation (elevational diversity gradient),[3] though this is less well-studied.[4]

Explaining the latitudinal diversity gradient has been called one of the great contemporary challenges of biogeography and macroecology (Willig et al. 2003, Pimm and Brown 2004, Cardillo et al. 2005).[5] The question "What determines patterns of species diversity?" was among the 25 key research themes for the future identified in 125th Anniversary issue of Science (July 2005). There is a lack of consensus among ecologists about the mechanisms underlying the pattern, and many hypotheses have been proposed and debated. A recent review [6] noted that among the many conundrums associated with the latitudinal diversity gradient (or latitudinal biodiversity gradient) the causal relationship between rates of molecular evolution and speciation has yet to be demonstrated.

Understanding the global distribution of biodiversity is one of the most significant objectives for ecologists and biogeographers. Beyond purely scientific goals and satisfying curiosity, this understanding is essential for applied issues of major concern to humankind, such as the spread of invasive species, the control of diseases and their vectors, and the likely effects of global climate change on the maintenance of biodiversity (Gaston 2000). Tropical areas play prominent roles in the understanding of the distribution of biodiversity, as their rates of habitat degradation and biodiversity loss are exceptionally high.[7]

  1. ^ a b Hillebrand, H. (February 2004). "On the generality of the latitudinal diversity gradient" (PDF). The American Naturalist. 163 (2): 192–211. doi:10.1086/381004. PMID 14970922. S2CID 9886026.
  2. ^ Sahney, Sarda; Benton, Michael J (7 April 2008). "Recovery from the most profound mass extinction of all time". Proceedings of the Royal Society B: Biological Sciences. 275 (1636): 759–765. doi:10.1098/rspb.2007.1370. PMC 2596898. PMID 18198148.
  3. ^ McCain, Christy M. (February 2005). "Elevational Gradients in Diversity of Small Mammals" (PDF). Ecology. 86 (2): 366–372. Bibcode:2005Ecol...86..366M. doi:10.1890/03-3147. S2CID 37759984. Archived from the original (PDF) on 2020-02-08.
  4. ^ Rahbek, Carsten (June 1995). "The elevational gradient of species richness: a uniform pattern?". Ecography. 18 (2): 200–205. Bibcode:1995Ecogr..18..200R. doi:10.1111/j.1600-0587.1995.tb00341.x.
  5. ^ Mora, Camilo; Robertson, D. Ross (July 2005). "Causes of latitudinal gradients in species richness: a test with fishes of the Tropical Eastern Pacific" (PDF). Ecology. 86 (7): 1771–1782. Bibcode:2005Ecol...86.1771M. doi:10.1890/04-0883. S2CID 35273509. Archived from the original (PDF) on 2019-03-07.
  6. ^ Dowle, E. J.; Morgan-Richards, M.; Trewick, S. A. (2013). "Molecular evolution and the latitudinal biodiversity gradient". Heredity. 110 (6): 501–510. doi:10.1038/hdy.2013.4. PMC 3656639. PMID 23486082.
  7. ^ Tittensor, Derek P.; Mora, Camilo; Jetz, Walter; Lotze, Heike K.; Ricard, Daniel; Berghe, Edward Vanden; Worm, Boris (August 2010). "Global patterns and predictors of marine biodiversity across taxa". Nature. 466 (7310): 1098–1101. Bibcode:2010Natur.466.1098T. doi:10.1038/nature09329. PMID 20668450. S2CID 4424240.