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Evolutionary Biology of Parasitism
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
One great model to assist in gaining an understanding of parasite speciation is provided by chewing lice (Phthiraptera: Trichodectidae) infesting pocket gophers (Geomyidae) (Figure 7.21). This parasite–host system has already been mentioned in the context of how limited gopher mobility favors the development of strong population substructure in their lice. Suppose a particular population of pocket gophers was to become subdivided geographically such that isolation, divergence and speciation occurred (note the element of small-scale allopatric separation involved here). What would be the fate of the lice on the gophers in each population? Given that the lice spend their entire lives on their hosts, that they have very little dispersal ability of their own, and that they must rely on the limited opportunities of host-to-host contact for their transmission, then it follows that the lice in the two host populations would be isolated as well. This separation might result in an accumulation of genetic differences, reproductive isolation and speciation.
Mobile DNA Sequences and Their Possible Role in Evolution
Published in S. K. Dutta, DNA Systematics, 2019
Georgii P. Georgiev, Yurii V. Ilyin, Alexei P. Ryskov, Tatiana I. Gerasimova
The difference between movable elements of various species may also contribute to their reproductive isolation. Such differences may appear, for example, instantly as a result of the infection of a particular population with the novel transposable element such as retrovirus or the P-factor, or the change of mobile element may be the result of its own evolution passing through a number of mutation-conversion steps. In this case, in a separate group of animals a changed mobile element may appear.
Classification and Systematics
Published in Jacques Derek Charlwood, The Ecology of Malaria Vectors, 2019
Interbreeding between populations that have ecologically diverged, by either niche specialisation or invasion of a new niche (such as the water bodies created during rice cultivation), produces hybrid individuals of lower fitness in each of the parental habitats. Ecological speciation theory predicts that reproductive isolation is environment-dependent; in other words, it is driven by ecological selective forces such as resource competition or predation. The strength of reproductive isolation is correlated with the degree of ecological divergence, rather than time since lineage splitting. Thus, the separation of, say, optimal breeding sites may result in ecological speciation. Although the incipient species may for many aspects occupy the same geographical space and the same niche (i.e., they are sympatric), at certain points they must be separated (i.e., they are allopatric). Not all available habitats may be occupied at any one time. Populations, particularly at the margins of the mosquitoes’ distribution, may become locally extinct leaving the habitat unoccupied until it is recolonised. In other words, they are likely to form a metapopulation.
Host population related variations in circadian clock gene sequences and expression patterns in Chilo suppressalis
Published in Chronobiology International, 2019
Li Zhu, Shuo Feng, Qiao Gao, Wen Liu, Wei-Hua Ma, Xiao-Ping Wang
C. suppressalis, a major global pest of rice crops, has distinguishable rice and water-oat populations (Hou et al. 2009; Maki and Yamashita 1956; Samudra et al. 2002; Zhong et al. 2017). Asynchrony in the sexual activity of these populations is thought to be one of the main reasons for the formation of these respective host races (Quan et al. 2016; Samudra et al. 2002; Ueno et al. 2006). Female calling is an important regulator of the timing of mating behavior in insects (Arbuthnott and Crespi 2009; Phelan and Baker 1990; Tanner et al. 2011). Asynchrony in female calling rhythm can lead to divergence in the timing of mating activity, and therefore a degree of reproductive isolation, between different host races (Arbuthnott and Crespi 2009; Schofl et al. 2009). In C. suppressalis, females of the rice population mainly call in the first half of scotophase, whereas females of the water-oat population generally begin calling in the second half of the scotophase (Quan et al. 2016; Ueno et al. 2006). However, the reason for this difference in behavior remains unclear.
A short guide to insect oviposition: when, where and how to lay an egg
Published in Journal of Neurogenetics, 2019
Kevin M. Cury, Benjamin Prud’homme, Nicolas Gompel
Another mechanism that can enable diversification of behavior on evolutionary timescales relies not on peripheral changes but rather on the modification of how sensory inputs are processed centrally (Figure 1(C)). Such a phenomenon has been observed in neural circuits that regulate courtship behavior between two closely related species, D. melanogaster and D. simulans, and serves as a mechanism that reinforces reproductive isolation between the two species (Seeholzer, Seppo, Stern, & Ruta, 2018). Though the males of both species detect a pheromone specific to D. melanogaster females using homologous sensory neurons, whether the signal promotes (D. melanogaster) or suppresses (D. simulans) courtship is determined by species-specific alterations in the balance of excitation and inhibition in downstream relays onto the neurons that regulate courtship. Perhaps, as is the case here, more dramatic shifts in behavior with regards to a sensory cue, such as a change in valence from positive to negative, may invoke central modifications as opposed to peripheral ones.
Mitochondrial DNA structure of an isolated Tunisian Berber population and its relationship with Mediterranean populations
Published in Annals of Human Biology, 2018
Nizar Ben Halim, Sana Hsouna, Khaled Lasram, Mariem Chargui, Laaroussi Khemira, Rachid Saidane, Sonia Abdelhak, Rym Kefi
The observed genetic structure of Douiret was confirmed at the phylogenetic analysis level. A clear genetic differentiation was observed between Berbers from Douiret and other Berber groups from Tunisia (Bou Omrane) and Algeria (Mozabites), which harbour more North African lineages (U6 and M1). Likewise, our sample does not cluster with other Berber communities from Tunisia like Sened, Bou Saad, Matmata, Jerba Berbers and Kesra revealing that the autochthonous inhabitants of Jebel Demmer, who make up the main maternal genetic background of Douiret, bear a particular mtDNA structure compared to other populations with the same Amazigh culture. In addition, Douiret was not connected to any European population (Figure 6). It seems that the different European migratory waves that have been experienced by Tunisia during its history (Romans, Vandals, Byzantines, Normans, Turkish, etc…) left no traces on this isolated community of South Eastern Tunisia. MDS plots also revealed the lack of affiliation between our sample and Moroccan populations. This gives evidence that migration from Morocco during Almohad and Hafsid times (1159–1574 AD), which concerned the whole country in general and Douiret in particular, could be exclusively composed of males. On the other hand, given the isolation of this community as shown by the high endogamy rates, it may be that genetic drift had a great role in the present haplogroup composition, by eliminating some lineages and enriching others. The position of our sample in the plot is also distant from the groups of Arab descent (Jerba Arabs, Moroccan Arabs). Thus, geographical proximity between Douiret and the surrounding Hilalian Arab tribes for nearly six centuries does not seem to be reflected in terms of genetic exchange. This is most probably explained by the intense reproductive isolation undergone by the community during its history, as evidenced by the very high rate of geographical and ethnical endogamy; 98.16% (Ben Halim, 2006).