Local Extinctions Related to Climate Change
Introduction
Climate change over the years may be a significant cause of biological diversity in the next century. Possible impacts of climate change on both plant and animal species survival remain uncertain as they are irregular. Studies have suggested that various loss of species in the future will occur due to climate change, the range being 0% to > 50% of all plant and animal types currently known. It is, therefore, vital to study the prevalence of local extinctions that relate to recent climate change.
Results
A total of 27 studies were conducted to substantiate the claims of potential climate-related warm-edge range shifts. The species that were sampled were widely spread across regions (animals = 716, plants = 260). Areas of origin; (Asia = 332, Europe = 268, Madagascar = 30, Oceania = 58, North America = 233, South America = 55). Of the 976 species sampled, 460 had warm-edge contractions, whereas 516 did not have warm edged contractions. 47.1% of the sample size (n=976), indicated that locally existent extinctions relating to climate change were highly common. This is concerning the relatively modest rise in global temperatures that has occurred recently (less than 1 Degree Celsius in global mean annual temperature).
Regression Analysis and Hypothesis Testing
Regression analysis was conducted for the proportion of species that experienced local extinctions against (1) the end date of the study, (2) the duration of the study, and (3) the study start date. These all yielded nonsignificant results (end date: r2 = 0.001, p=0.1376, the duration: r2= 0.045, p= 0.2896, end date: r2= 0.146, p=0.2788). In general, the frequency of local extinctions was similar across climatic zones, natural habitats, gradients, and clades (almost 50%). However, there were different and significant observations.
Local extinctions were more common in the tropical and subtropical areas as compared to the temperate regions (p< 0.0001; Chi-square test, testing the assumption of equal frequencies in different climate zones). Particularly, 54.6% of the 504 comprised of tropical species which had local extinctions while just 39.2% of the 472 temperate species did. The pattern was even stronger when terrestrial species on elevational gradients were considered (54.6% of 504 tropical species against 28.2% of 301 temperate species). This applied to all plants but most animals. This pattern of more extinction frequencies in tropical species came up from a lower frequency of extinctions from temperate plants (59.4% of 155 tropical species versus 8.6% of 105 temperate species, p<0.0001). For tropical and temperate species in elevational gradients, the pattern was similar (52.4% of 349 tropical animal species versus 38.8% of 196 temperate species, p= 0.0022). Across animals, the difference in frequencies was not significant (0.2309), probably because of the influence of marine and freshwater. Tropical extinction was significant in birds (p= 0.0284, 51.4% of 109 tropical species versus 37.1% of 124 temperate species) but not significant in birds (55.2% 0f 210 tropical species versus 59.0% of 61 temperate species, p= 0.6007).
Conclusion
The results showed that there were, in general, similar patterns of extinction across climatic zones. However, local extinctions were more significant in tropical species and animals. The climate changes had adversely affected species in tropical species as compared to temperate species (54.6% versus 39.2%). These patterns are more robust in pants than in animals, however. In general, these results support that the negative impacts of climate change on biological diversity are more frequent in tropical regions where there is diversity in species.
References
Wiens, J. J. (2016). Climate-related local extinctions are already widespread among plant and animal species. PLOS Biology, 14(12), e2001104. https://doi.org/10.1371/journal.pbio.2001104