Data from: Habitat fragmentation, not habitat loss, drives the prevalence of blood parasites in a Caribbean passerine

Habitat destruction due to human land-use activities is well recognized as a central threat to biodiversity. However, there is still debate about the relative influence of its two components, habitat loss and habitat fragmentation, mostly because few studies have been able to disentangle their respective effects. We studied mechanisms by which habitat destruction might influence the prevalence of vector-transmitted haemosporidian blood parasites of the genera Plasmodium and Haemoproteus the Lesser Antillean Bullfinch, Loxigilla noctis, on the Caribbean islands of Guadeloupe and Martinique . Starting from a large set of environmental descriptors (including metrics reflecting habitat loss, habitat fragmentation and landscape heterogeneity; as well as other variables not linked to habitat destruction, such as climatic conditions), we used PLS regression analyses to determine which variables were driving parasite prevalence on the islands. Our results showed that variables related to forest destruction were much more influential than other factors for all parasites analyzed on both islands. Remarkably, the effects documented were almost exclusively due to forest fragmentation, as opposed to habitat loss. This positive effect of forest fragmentation on blood parasite prevalence is proposed to happen through its effects on insect vectors and/or host biology. Increased understanding of the role of habitat fragmentation as a driver of parasitic diseases can help anticipate future effects and limit the risk of emergence and proliferation of wildlife pathogenic outbreaks and zoonosis through informed landscape planning.

人类土地利用活动引发的生境破坏，已被学界公认为威胁生物多样性的核心因素之一。然而，生境破坏的两个组成部分——生境丧失（habitat loss）与生境破碎化（habitat fragmentation）——的相对影响仍存在争议，这主要是因为鲜有研究能够厘清二者各自的生态效应。本研究以加勒比海瓜德罗普岛（Guadeloupe）与马提尼克岛（Martinique）上的小安的列斯牛雀（Loxigilla noctis）为研究对象，探究生境破坏可能通过何种机制，影响其体内媒介传播性血孢子虫血液寄生虫（隶属于疟原虫属（Plasmodium）与血变原虫属（Haemoproteus））的感染率。本研究采集了多类环境描述因子：既包括反映生境丧失、生境破碎化与景观异质性的量化指标，也涵盖与生境破坏无关的气候条件等其他变量，随后采用偏最小二乘（PLS）回归分析，明确驱动两岛寄生虫感染率的关键变量。研究结果显示，相较于其他影响因子，与森林破坏相关的变量对两岛所有被分析寄生虫的感染率影响更为显著。值得注意的是，本研究记录到的效应几乎完全源自森林破碎化，而非生境丧失。我们提出，森林破碎化对血液寄生虫感染率的这种正向影响，可能通过其对昆虫媒介以及/或宿主生物学特性的作用得以实现。加深对生境破碎化作为寄生虫病驱动因子的认知，有助于通过科学合理的景观规划，预测其未来影响，并降低野生动物病原暴发与人畜共患病（zoonosis）的出现与扩散风险。