Signs of Urban Evolution? Morpho-Functional Traits Co-variation Along a Nature-Urban Gradient in a Chagas Disease Vector

Abstract

Environmental change (i.e., urbanization) impacts species in contrasting ways, with some species experiencing benefits given their way of life (i.e., blood-sucking insects). How these species respond to such change is not well understood and for species involved in human diseases, this “how” question is particularly important. Most Triatominae bug species inhabit tropical and subtropical forests where their vertebrate hosts’ temporal abundance depends on climate seasonality. However, in human encroached landscapes, triatomines can benefit from resource stability which may lead to adaptive phenotypic change to track novel hosts. We tested for an association between different landscapes and morpho-functional traits linked to sensory, motion, and feeding functions in Triatoma dimidiata and compared fecundity (i.e., number of eggs) in each landscape as a proxy of fitness. Using geometric and traditional morphometric tools, we predicted a morphological simplification in bugs inhabiting urbanized areas. While wing morphology or proboscis were not influenced by landscape class, the opposite occurred for thorax morphology and number of sensilla. Wing and thorax morphology did not covary under modified landscape scenarios, yet we detected a morpho-functional convergence for thorax size and antennal phenotype in both sexes, with a simplification trend, from nature to urban settings. Given no fecundity differences across landscapes, there is no potential reproductive costs. Moreover, the convergence of thorax size and antennal phenotype suggests differences in flight/locomotion performance and host/environment perception, as a possible adaptive response to relaxed selective pressures of the bug’s native habitat. These results imply that T. dimidiata could be adapting to urbanized areas.

An overview of the trypanosomatid (Kinetoplastida: Trypanosomatidae) parasites infecting several mammal species in Colombia

“…Considering the identified parasite species versus those expected in wild mammals and coinfection events, a new scenario is opening showing the need for research on the following topics: (i) the role of domestic/wild mammals and vectors in the maintenance of transmission cycles, which has been studied and proposed in mathematical models for different vector-borne diseases [98][99][100]; (ii) the domiciliation transition of vectors in specific areas, phenomena highly relevant for American trypanosomiasis and VL in recent years [101][102][103]; (iii) the possibility of the genetic recombination of the different actors implicated in the parasites' life cycle, not just for the vector context [104][105][106]. The latter must transcend the world view of human diseases and recognize their importance and the veterinary diseases that must be equally prioritized in the public health systems [107].…”

Does Trypanosoma cruzi (Chagas, 1909) (Kinetoplastida: Trypanosomatidae) modify the antennal phenotype of Triatoma dimidiata (Latreille, 1811) (Hemiptera: Triatominae)?

“…Therefore, the question remains whether the observed morphological differences are explained by the direct effect of T. cruzi infection and host manipulation, are evolutionary responses to selection at the population level, or are the consequences of different causal factors such as microecological influences [ 85 ].…”

Relationship between flight muscle dimorphism and wing morphometry in Triatoma infestans (Klug, 1834) (Hemiptera, Reduviidae, Triatominae)

“…Furthermore, domestic habitats had near-optimum temperatures for T. infestans and more capacity to damp variations in external conditions than other frequently infested peridomestic ecotopes (Vázquez-Prokopec et al, 2002). For T. dimidiata (Latreille, 1811), another triatomine species, the comparison of urban and rural insects showed evidence of adaptation to urban areas for morpho-functional related traits (Montes de Oca-Aguilar et al, 2022). For T. infestans the effect of habitat had been demonstrated for different traits such us wing, head and antennal phenotype (Schachter-Broide et al, 2004;Hernández et al, 2011).…”