Bansal Udita, Thaker Maria
Centre for Ecological Sciences, Indian Institute of Science, Bangalore, India.
Glob Ecol Biogeogr. 2021 Dec;30(12):2431-2441. doi: 10.1111/geb.13396. Epub 2021 Sep 28.
Latitudinal gradients in life-history traits are apparent in many taxa and are expected to be strong for ectotherms that have temperature-driven constraints on performance and fitness. The strength of these gradients, however, should also be affected by diet. Because diet type (carnivory, omnivory, herbivory) influences accessibility to nutrition and assimilation efficiency, we aim to study how diet affects latitudinal gradients in lifetime reproductive output and the underlying life-history traits in ectotherms.
Global.
Recent.
Lizards (Reptilia, Squamata, Sauria).
We used empirical (352 species) and phylogenetically imputed data (563 species) to analyse the interactive effects of latitude and diet on life-history traits (longevity, age at maturity, reproductive life span, hatchling mass, clutch/brood size, clutch/brood frequency, female mass) and lifetime reproductive output of lizards.
Lifetime reproductive output does not significantly differ in lizards across diet types, and only carnivores exhibit a small increase at higher latitudes. Diet type, however, influences latitudinal patterns of individual life-history traits. Carnivores exhibit a shift towards 'slower-paced' life histories at higher latitudes for most traits (increased longevity, age at maturity, reproductive life span, and decreased clutch frequency). By contrast, herbivores either display 'faster-paced' life histories (reduction in reproductive life span, hatchling mass, female mass) or no change (clutch frequency, clutch size, age at maturity) at higher latitudes. Omnivores exhibit intermediate and muted latitudinal patterns.
We suggest that the nutritional challenges of herbivory, compounded by thermal constraints at higher latitudes, may explain differences in life-history characteristics of herbivorous ectotherms. Intermediate patterns exhibited by omnivores highlight how flexibility in diet can buffer environmental challenges at higher latitudes. Our results indicate that lizards with different diet types display various trends in their life histories across latitudes, which eventually balance out to result in similar reproductive outputs throughout their lifetime, with little benefits to carnivory.
生活史特征的纬度梯度在许多生物分类群中都很明显，对于受温度驱动影响性能和适合度的变温动物而言，这种梯度预计会很强。然而，这些梯度的强度也应受饮食的影响。由于饮食类型（肉食性、杂食性、草食性）会影响营养获取和同化效率，我们旨在研究饮食如何影响变温动物一生繁殖产出的纬度梯度以及潜在的生活史特征。
全球。
近期。
蜥蜴（爬行纲，有鳞目，蜥蜴亚目）。
我们使用实证数据（352个物种）和系统发育推断数据（563个物种）来分析纬度和饮食对蜥蜴生活史特征（寿命、成熟年龄、繁殖寿命、幼体质量、窝卵数/窝仔数、窝卵/窝仔频率、雌性体重）和一生繁殖产出的交互作用。
不同饮食类型的蜥蜴一生繁殖产出无显著差异，只有肉食性蜥蜴在高纬度地区有小幅增加。然而，饮食类型会影响个体生活史特征的纬度模式。对于大多数特征，肉食性蜥蜴在高纬度地区呈现出向“节奏较慢”的生活史转变（寿命延长、成熟年龄增加、繁殖寿命延长、窝卵频率降低）。相比之下，草食性蜥蜴在高纬度地区要么呈现“节奏较快”的生活史（繁殖寿命缩短、幼体质量降低、雌性体重降低），要么没有变化（窝卵频率、窝卵数、成熟年龄）。杂食性蜥蜴呈现出中等且不明显的纬度模式。
我们认为，草食性带来的营养挑战，再加上高纬度地区的热限制，可能解释了草食性变温动物生活史特征的差异。杂食性蜥蜴呈现的中等模式突出了饮食灵活性如何缓冲高纬度地区的环境挑战。我们的结果表明，不同饮食类型的蜥蜴在不同纬度的生活史呈现出各种趋势，最终这些趋势相互平衡，导致它们一生的繁殖产出相似，肉食性并没有太大优势。
