The macroparasite fauna of cichlid fish from Nicaraguan lakes, a model system for understanding host–parasite diversification and speciation

Abstract

The Nicaraguan lakes represent an ideal continent-island-like setting to study the colonization patterns of both fish and their parasites. The dominant fish fauna are cichlids, particularly the Midas cichlid species complex Amphilophus spp., a well-studied model for recent sympatric speciation. Here, we characterized the Midas cichlid macroparasite diversity in Nicaraguan lakes. We evaluated patterns of parasite diversity across host populations. Morphological and molecular analyses were conducted, revealing a macroparasite fauna composed by 37 taxa, including platyhelminths, nematodes, copepods, branchiurans, hirudineans and oribatids. Three invasive species are reported for the first time. The Midas cichlid was infected by 22 parasite taxa, 18 shared with other cichlids. Eight taxa conformed the core parasite fauna of the Midas cichlid. The large lakes had higher parasite diversity than the smaller and isolated crater lakes, although parasite infracommunity diversity was lower. Environmental factors along with the differential distribution of intermediate hosts, the potential resistance gained by their hosts after colonization of new lakes, competitive exclusion among parasites, or the introduction of exotic fish, may determine the observed pattern of parasite heterogeneous distribution. Our study provides a ground to explore the evolutionary history of both, hosts and parasites within the context of speciation and diversification processes.

Filling the knowledge gap of Middle American freshwater fish parasite biodiversity: metazoan parasite fauna of Nicaragua

“…The present study represents an additional step to an ongoing effort to characterize the metazoan parasites of Nicaraguan fish (see Santacruz et al ., 2020, 2021, 2022). Here, we report new data on the parasite fauna of non-cichlid fish hosts.…”

“…The procedures to sample, maintain and euthanize the fish specimens followed those described in Santacruz et al . (2022), and followed procedures approved by the American Veterinary Medical Association Guidelines for Euthanasia of Animals, 2020 edition (available at ). All parasites recovered were counted, and representative samples of each morphotype were fixed for morphological or molecular study in hot formalin or molecular-grade ethanol, respectively.…”

“…All parasites collected were analysed morphologically to achieve the highest taxonomic resolution following Santacruz et al . (2022). Morphological vouchers of some species, and in some cases hologenophores ( sensu Pleijel et al ., 2008), were deposited at the Colección Nacional de Helmintos (CNHE), Universidad Nacional Autónoma de México, Mexico City, with the accession numbers 11,482, 11,491, 11,492, 11,497, 11,499, 11,500 and 11,503.…”

“…Fish were sampled in three consecutive years (2017)(2018)(2019), at the end of the rainy season (November and December), in the two great lakes Nicaragua and Managua and in four crater lakes (Asososca León, Xiloá, Masaya and Apoyo). The procedures to sample, maintain and euthanize the fish specimens followed those described in Santacruz et al (2022), and followed procedures approved by the American Veterinary Medical Association Guidelines for Euthanasia of Animals, 2020 edition (available at https://www.avma.org/sites/default/files/2020-02/ Guidelines-on-Euthanasia-2020.pdf). All parasites recovered were counted, and representative samples of each morphotype were fixed for morphological or molecular study in hot formalin or molecular-grade ethanol, respectively.…”

“…Also, some nematodes were reported from crater lakes Xiloá and Apoyo (González-Solís & Jiménez-García, 2006). Recently, intensive survey work aimed at describing the metazoan parasite fauna of cichlids, with an emphasis on the Midas cichlid species complex, yielded the description of an additional set of species (Santacruz et al, 2020(Santacruz et al, , 2021(Santacruz et al, , 2022.…”