Source: Korstjens, A. H., & Hillyer, A. P. (2016). Primates and climate change: A review of current knowledge. An introduction to primate conservation, 175-192.
Part One: Impacts
As I wrote about in my last post about assessing vulnerability (Graham et al, 2016), we know that climate change will affect both temperature and precipitation. Whilst scientists are still struggling to find ways to predict how primates will respond to climate change, there are four changes that could occur as a result of climate change: phenology, habitat shifts, community changes and disease.
An obvious effect of change in temperature is that ecosystem is going to be knocked out of its’ current rhythm. Fluctuations in the timing of phenological events is expected to become more irregular and more extreme. Changes affecting food sources could lead to asynchrony between life cycles of predators and prey, parasitoids and hosts, pollinators and plants, and primates and their food sources. In relation to primates, those who have synchronised their reproductive events to fit seasonal patterns of resource availability are particularly at risk .
With seasonal food availability fluctuating, this leads onto the larger problem of habitat shifts and fragmentation. With changing climatic conditions, suitable habitats begin to shift but can also become fragmented, reduced or in some cases, expanded. As temperature is driving a lot of climatic changes, most shifts are on the altitudinal gradient and/or on the latitudinal gradient.
Luo et al. (2015), found that the range of the Sichuan snub-nosed monkey could reduce by almost 30% by 2020, 70% by 2050, and over 80% by 2080. Over time, the monkeys will be forced to migrate to higher elevations.
Climate change can also lead to habitat fragmentation, which limits migration (important for gene flow and repopulation of suitable areas) and access to food sources. A major reduction in rainfall in Senegal has led to habitat fragmentation and degradation, increasingly endangering the survival of the already range-restricted Temminickii’s red colobus (Galat et al. 2009). Meanwhile, climate change is expected to cause severe habitat shifts and fragmentation for orang-utans (Gregory et al. 2012).
There is also the somewhat unpredictable effect on the composition of animal communities, as each individual species will respond in a different way. With one species of the forest community gone, other species may be able to flourish due to reduced competition, a process known as density compensation. One such example is that when larger bodied Neotropical primates are hunted, medium-sized species become more abundant (Peres and Dolman 2000). Equally, this also presents a problem because predators may then change their preference to the more abundant species, leading to a negative effect.
With hotter and wetter climates, comes the greater likelihood that pathogens can develop, survive and spread. Inevitably, this would lead to an increase in the prevalence and severity of diseases. Diseases that spread via mosquitoes are expected to expand latitudinally with increasing temperatures.
A study on lemur parasites (mites, ticks and worms) found that the projected changes in Madagascar’s climate would lead to range expansion for most parasites. It was the most harmful parasites that had the greatest expansion, while most primate ecto- and endo-parasite indices, such as richness and abundance, increased during warmer, wetter conditions (Barrett et al. 2013). Similar findings were discovered for parasites in chimpanzees (Huffman et al. 1997) and ursine colobus (Teichroeb et al. 2009).
Elsewhere, parasite prevalence in mantled howler monkeys was higher around water bodies and in wet forests compared with dry forests (Stoner 1996) and wetter areas of forest correlated positively with indices of parasite infections in eastern black-and-white colobus (Chapman et al. 2010a).
The increase in the severity and potential frequency of storms could also expose primates to pathogens, as was discovered by Behie et al. (2014). Following a hurricane in Belize, they found that black howler monkeys had a higher exposure to the trematode Controrchis spp.
Whilst I’ve written the different impacts separately, as they appeared in the literature, they are not exclusive of each other. Take lemurs as an example. They have weaning synchrony, meaning that they lactate during the period of fruit availability, in fact the smallest species of lemur can fit its’ entire breeding cycle into the peak fruiting season (Wright 2006). If the fruiting season becomes more irregular as a result of climate change, then reproductive success and overall health will drop. In addition to that, the prevalence of lemur parasites (including the most harmful) will increase because the climate is warmer and wetter.
This will mean that there will be fewer lemurs, due to lower reproductive success, who also have a higher exposure to disease and most likely lower immunity (due to a sparser food supply). Sadly, I believe this could lead to a population decline across the board for lemurs.
Barrett, M. A., Brown, J. L., Junge, R. E., & Yoder, A. D. (2013). Climate change, predictive modeling and lemur health: assessing impacts of changing climate on health and conservation in Madagascar. Biological Conservation, 157, 409-422.
Behie, A. M., Kutz, S., & Pavelka, M. S. (2014). Cascading effects of climate change: do hurricane‐damaged forests increase risk of exposure to parasites?. Biotropica, 46(1), 25-31.
Chapman, C. A., Speirs, M. L., Hodder, S. A., & Rothman, J. M. (2010). Colobus monkey parasite infections in wet and dry habitats: implications for climate change. African Journal of Ecology, 48(2), 555-558.
Galat, G., Galat-Luong, A., & Nizinski, G. (2009). Increasing dryness and regression of the geographical range of Temminck’s red colobus Procolobus badius temminckii: implications for its conservation.
Gregory, S. D., Brook, B. W., Goossens, B., Ancrenaz, M., Alfred, R., Ambu, L. N., & Fordham, D. A. (2012). Long-term field data and climate-habitat models show that orangutan persistence depends on effective forest management and greenhouse gas mitigation. PloS one, 7(9), e43846.
Huffman, M. A., Gotoh, S., Turner, L. A., Hamai, M., & Yoshida, K. (1997). Seasonal trends in intestinal nematode infection and medicinal plant use among chimpanzees in the Mahale Mountains, Tanzania. Primates, 38(2), 111-125.
Luo, Z., Zhou, S., Yu, W., Yu, H., Yang, J., Tian, Y., … & Wu, H. (2015). Impacts of climate change on the distribution of Sichuan snub‐nosed monkeys (Rhinopithecus roxellana) in Shennongjia area, China. American journal of primatology, 77(2), 135-151.
Peres, C. A., & Dolman, P. M. (2000). Density compensation in neotropical primate communities: evidence from 56 hunted and nonhunted Amazonian forests of varying productivity. Oecologia, 122(2), 175-189.
Stoner, K. E. (1996). Prevalence and intensity of intestinal parasites in mantled howling monkeys (Alouatta palliata) in northeastern Costa Rica: implications for conservation biology. Conservation Biology, 10(2), 539-546.
Teichroeb, J. A., Kutz, S. J., Parkar, U., Thompson, R. A., & Sicotte, P. (2009). Ecology of the gastrointestinal parasites of Colobus vellerosus at Boabeng‐Fiema, Ghana: Possible anthropozoonotic transmission. American Journal of Physical Anthropology: The Official Publication of the American Association of Physical Anthropologists, 140(3), 498-507.
Wright, P. C. (2006). Considering climate change effects in lemur ecology and conservation. In Lemurs (pp. 385-401). Springer, Boston, MA.