Effect of climate change on the Neotropics

Whereas my last posts have looked into the findings of a single paper, this post will include research from several. These will cover the effects of climate change (Korstjens & Hillyer, 2016; Ribeiro et al. 2020); including a deeper look into its’ effect on primate metapopulations (Wiederholt & Post 2010), and a case study looking at the impact on lion tamarins (Sales et al. 2020).

On a wider scale, a 2013 report from the Intergovernmental Panel on Climate Change (IPCC) predicted mean temperature increases in most land and ocean regions (high chance); hot extremes in inhabited regions (high chance); heavy precipitation in several regions (medium chance); and drought and precipitation deficits in some regions (medium chance). It goes without saying that different regions of the world will be affected in different ways, and this post will focus on the neotropics – Central and South America.

It’s predicted that some areas of forest will change to savannah woodland, which poses a problem for fully arboreal primates. This includes those from the atelinae subfamily, including spider monkeys (left), woolly monkeys (top right) and muriquis (bottom right). These primates may well struggle to adapt to a habitat that requires regular terrestrial travel.

Impact of the El Nino and La Nina effect

It is also predicted that climate change will increase El Nino and La Nina events which can strongly affect primates. The warming (El Nino) and cooling phases (La Nina) of the El Nino-Southern Oscillation (ENSO) can affect global weather systems, however they can also be associated with extreme precipitation events in different regions of South America. El Nino events cause an area of reduced heavy rainfall in the northern region, with the strongest impact occurring in March. La Nina events cause the opposite, with areas of increased precipitation in the north and reduced precipitation in the south, with the strongest impacts occurring in April (Grimm &Tedeschi, 2009) .

It’s noteworthy that there’s a particularly strong effect on the weather in the southern region. During El Nino events, there is a strong and consistent increase in extreme events over the Paraná/La Plata river basin which has been connected with strong flooding (Grimm &Tedeschi, 2009). It is also the location of the most intense storms on earth, especially during November (Zipser et al. 2006).

Research by Wiederholt & Post (2010) found that the population size of atelines decreased either immediately or one year after an El Nino event as a result of a reduction in food availability. The frugivorous atelines also had a stronger response than the folivorous howler monkeys.

Effects of ENSO on rainfall in South America. Left: El Nino, Right: La Nina (Munoz et al. 2016)

The results of Wiederholt and Post’s study could indicate the potential future that atelines face. Dry conditions, El Nino events and increased mean annual temperature lead to lower birth rates and affected the sex ratio at birth in frugivorous woolly monkeys and northern muriquis. Some of the damage can be offset by diet flexibility, for example owl monkeys (Aotus azarai) responded to drought by increasing the percentage of leaves in the normally very frugivorous diet (Fernandez-Duque and Heide 2013).

Impact on metapopulations

Basically speaking, a metapopulation is a population of subpopulations within a defined area, that have the ability to move between each area. While individual populations have finite lifespans – they’re affected by demographic stochasticity (fluctuations in population size due to random demographic events); the metapopulation as a whole is stable because they can re-colonise habitat previous left by a recently extinct subpopulation. A declining subpopulation may also be saved from extinction by the emigration of new members from a neighbouring subpopulation (called the rescue effect).

The danger of climate change is that it could negatively impact all the subpopulations at the same time, reducing the ability of one subpopulation to rescue or replace the dying out one. It’s been found that the more frugivorous primate populations exhibit a higher degree of population synchrony over distance. According to metapopulation theory, it is these populations that have a greater extinction risk than those with more asynchronous populations dynamics.

An increase in El Nino events and the annual mean temperature will affect multiple ecosystems at a time, and given the previously documented impact on atelines, there is a serious threat that the metapopulations as a whole could be weakened. Add this to an already highly endangered group and you have a very credible threat of multiple extinctions.

Case Study – Exposure of lion tamarins (Leontopithecus spp.) to climate change

Source: Meyer, A. L., Pie, M. R., & Passos, F. C. (2014). Assessing the exposure of lion tamarins (Leontopithecus spp.) to future climate change. American Journal of Primatology76(6), 551-562.

Lion tamarins are among the most threatened primates in the world. Due to a limited dispersal capacity and low genetic diversity, they are also particularly vulnerable to environmental perturbations. Current research points to the loss of climatically suitable habitats by 2080, an almost inevitable road to extinction.

The golden-headed lion tamarin (L. chrysomelas) is facing an increasing reduction of remnant size, coupled with with population isolation. Those in the western ranges face substantial local extinction threats due to continuing damage to the Brazilian Atlantic Forest. Additionally, there is evidence that northeast Brazil is going through a process of desertification. Ultimately, this means the potential loss of the only remnant large enough to harbour a viable population of golden-headed lion tamarins (Pictured middle left).

This isn’t to suggest that conservation efforts haven’t worked. A program involving the golden lion tamarin (L. rosalia) has been successful, however only six of these populations were found to be potentially viable over the long-term. Unfortunately, climate suitability will only be kept in small-scattered patches, most of which are located away from extant populations. By 2050, the only remnant large enough to sustain the population will have lost its’ climate suitability.

The black lion tamarin (L. chrysopygus) with only 1000 individuals remaining, is likely the most at risk of isolation. It’s sparsely spread out across 11 populations in Sao Paulo, with the Morro do Diabo State Park being the only area with long-term viability. This particular location is vital for the metapopulational management of the species. However, by 2080, a large portion of the species’ range will be exposed to climate change, including the Morro do Diabo State Park.

N.B. Morro do Diabo State Park borders the state of Parana, mentioned earlier in the section about El Nino and La Nina events.

By 2080, key populations of L. rosalia, L. chrysomelas and L. chrysopygus will be exposed to climate change.

References

Grimm, A. M., & Tedeschi, R. G. (2009). ENSO and extreme rainfall events in South America. Journal of Climate22(7), 1589-1609.

Meyer, A. L., Pie, M. R., & Passos, F. C. (2014). Assessing the exposure of lion tamarins (Leontopithecus spp.) to future climate change. American Journal of Primatology76(6), 551-562.

Muñoz, Ángel & Thomson, Madeleine & Goddard, Lisa & Aldighieri, Sylvain. (2016). The Latin American and Caribbean Climate Landscape for ZIKV Transmission. 10.7916/D8X34XHV.

Sales, L., Ribeiro, B. R., Chapman, C. A., & Loyola, R. (2020). Multiple dimensions of climate change on the distribution of Amazon primates. Perspectives in Ecology and Conservation18(2), 83-90.

Wiederholt, R., & Post, E. (2010). Tropical warming and the dynamics of endangered primates. Biology Letters6(2), 257-260.

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