how does climate influences on distribution of population growth
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Answer:
Climate often drives ungulate population dynamics, and as climates change, some areas may become unsuitable for species persistence. Unraveling the relationships between climate and population dynamics, and projecting them across time, advances ecological understanding that informs and steers sustainable conservation for species. Using pronghorn (Antilocapra americana ) as an ecological model, we used a Bayesian approach to analyze long‐term population, precipitation, and temperature data from 18 populations in the southwestern United States. We determined which long‐term (12 and 24 months) or short‐term (gestation trimester and lactation period) climatic conditions best predicted annual rate of population growth (λ). We used these predictions to project population trends through 2090. Projections incorporated downscaled climatic data matched to pronghorn range for each population, given a high and a lower atmospheric CO2 concentration scenario. Since the 1990s, 15 of the pronghorn populations declined in abundance. Sixteen populations demonstrated a significant relationship between precipitation and λ, and in 13 of these, temperature was also significant. Precipitation predictors of λ were highly seasonal, with lactation being the most important period, followed by early and late gestation. The influence of temperature on λ was less seasonal than precipitation, and lacked a clear temporal pattern. The climatic projections indicated that all of these pronghorn populations would experience increased temperatures, while the direction and magnitude of precipitation had high population‐specific variation. Models predicted that nine populations would be extirpated or approaching extirpation by 2090. Results were consistent across both atmospheric CO2 concentration scenarios, indicating robustness of trends irrespective of climatic severity. In the southwestern United States, the climate underpinning pronghorn populations is shifting, making conditions increasingly inhospitable to pronghorn persistence. This realization informs and steers conservation and management decisions for pronghorn in North America, while exemplifying how similar research can aid ungulates inhabiting arid regions and confronting similar circumstances elsewhere.
Introduction
Variations in climate affect the growth, development, fecundity, and demographic trends in ungulates, thereby driving their population dynamics (Sæther 1997, Post and Stenseth 1999). Unravelling such relationships between species and climate provides critical information for advancing ecological understanding and targeting management actions. Ecologically, as climates change, some areas may become unsuitable for species that historically inhabited them (Luo et al. 2015). These species must move elsewhere or perish (see Minteer and Collins 2010). Therefore, understanding the relationships between climate and a species' ecology helps wildlife managers formulate conservation strategies. For example, any resources put towards conserving a species in an area that is projected to become unsuitable, may only delay the inevitable population declines, thereby risking unwise conservation investments. Sustainable approaches would focus effort on the locations where habitat conditions will remain viable, or where new habitats may arise (or could be restored), to ensure that enough, quality habitat persists for the species. By doing so, the conservation and management strategies that biologists pursue, and the locations where they work, align with the climatological, and hence ecological, trajectory of a site. Clearly, identifying which climatic drivers affect populations most, and resolving how and where they operate now and into the future, will provide ecologists and management professionals the necessary information to inform and steer species conservation.
Biologists have already documented the effects of climate change on ungulates. In northern Europe, increasingly warm and wet winters led to a decrease in body mass of red deer (Cervus elaphus ), reducing their survival and reproductive success (Post et al. 1997). In Alaska, earlier onset of plant emergence from warmer springs reduced calving success in caribou (Rangifer tarandus ), due to trophic and spatial asynchrony (Post et al. 2008). Adult survival rates in moose (Alces alces ) decreased with increasing ambient temperatures, resulting in lower moose densities, and ultimately, a northward shift in the southern boundary of their distribution (Lenarz et al. 2009, Dou et al. 2013). Lastly, in a study encompassing 16 populations of seven ungulates, Post and Stenseth (1999) revealed that large‐scale climatic variability influenced growth, development, and fecundity of these species, which led to declines in 14 of the populations.