Hematological parameters of a Neotropical wild frog population, with a phylogenetic perspective on blood cell composition in Anura

Hematological parameters can provide key information to an animal health status. However, this information is usually hard to obtain. Here, we described hematological parameters of <i>Leptodactylus podicipinus</i> in the Brazilian Pantanal. We measured red blood cell morphometrics, erythrogram, and leukogram. We also tested for phylogenetic signal in erythrogram and leukogram of 48 frog species from 15 families, testing if body size explains their variation. Lymphocytes were the most abundant leukocytes (&gt;60%) in <i>Leptodactylus podicipinus</i>, followed by neutrophils (~10%). Given that <i>L. podicipinus</i> is an abundant and widely distributed species in central Brazil, knowing its hematological pattern can help stablish a baseline and improve its use as a bioindicator of environmental degradation. Mean corpuscular hemoglobin and value contributed more to the phylomorphospace of erythrogram, in which <i>Leptodactylus</i> spp. and <i>Hypsiboas raniceps</i>had lower values of these variables, while <i>Bufotes viridis</i> and <i>Hyla arborea</i> had high values. The phylogenetic signal was spread throughout the dimensions of leukogram phylomorphospace. The variables that most contributed to it were lymphocyte counts, leukocytes and neutrophil counts. We also found a moderate phylogenetic signal for both the erythrogram and leukogram. Accordingly, body size accounted for a low proportion of variation in both the leukogram (4.7%) and erythrogram (0.57%). By combining phylogenetic comparative methods with hematological parameters, our results add a new perspective on the evolution of blood cell physiology in frogs.

血液学参数可为动物健康状况提供关键信息，然而此类信息通常较难获取。本研究针对巴西潘塔纳尔湿地的尖口细趾蟾（Leptodactylus podicipinus）的血液学参数进行了描述，测定了其红细胞形态计量学指标、红细胞谱及白细胞谱；同时针对15个科的48种蛙类的红细胞谱与白细胞谱检测了系统发育信号，并分析体型大小是否能够解释这些参数的变异。尖口细趾蟾的白细胞中，淋巴细胞占比最高（＞60%），其次为中性粒细胞（约10%）。鉴于该蟾是巴西中部分布广泛且数量丰富的物种，明确其血液学模式有助于建立基准参考，并提升其作为环境退化生物指示物的应用价值。平均红细胞血红蛋白量及相关指标对红细胞谱的系统发育形态空间贡献最大，其中细趾蟾属（Leptodactylus spp.）和锯腿小树蛙（Hypsiboas raniceps）的此类指标数值较低，而绿蟾蜍（Bufotes viridis）和欧洲树蛙（Hyla arborea）的数值较高。系统发育信号广泛分布于白细胞谱系统发育形态空间的各个维度，对此贡献最大的指标为淋巴细胞计数、白细胞总数及中性粒细胞计数。本研究同时发现，红细胞谱与白细胞谱均存在中等强度的系统发育信号；据此，体型大小对白细胞谱（4.7%）和红细胞谱（0.57%）变异的解释占比均较低。本研究将系统发育比较方法与血液学参数相结合，其结果为蛙类血细胞生理的演化研究提供了全新视角。