Sympatric speciation in Yponomeuta: no evidence for host plant fidelity (original) (raw)
Related papers
Journal of Organic Chemistry, 2005
Changes in host acceptance is an important factor in the host specialization of phytophagous insects, and knowledge of the genetic organization of this behaviour is necessary in order to understand how host shifts occur. Here we describe the inheritance of adult host acceptance (oviposition) in three closely related species of Yponomeuta Latreille (Lepidoptera: Yponomeutidae), and their interspecific hybrids. Yponomeuta cagnagellus (Hübner), a specialist on Euonymus europaeus L. (Celastraceae), Y. malinellus Zeller, a specialist on Malus spp. (Rosaceae), and Y. padellus (L.), oligophagous on a number of Rosaceae, were tested for their acceptance of parental hosts in choice tests. Acceptance of E. europaeus is semi-dominant in hybrids of Y. cagnagellus × Y. padellus , and in hybrids of Y. cagnagellus × Y. malinellus . The dominance of this acceptance was confirmed in oviposition tests with backcross hybrids: backcross hybrids F1 × Y. cagnagellus oviposited mainly on E. europaeus and F1 × Y. padellus still deposited more than half of their egg masses on E. europaeus . Reciprocal hybrids did not differ in their host acceptance, indicating that the trait is autosomal. We further studied the effect of larval food on adult host acceptance ('Hopkins host selection principle') in split full-sib F1 families. Larval diet influenced oviposition only in one of two hybrid crosses. The F1 hybrid of Y. padellus × Y. cagnagellus , reared on Prunus spinosa L . , deposited a significantly lower percentage of egg masses on E. europaeus compared to their full-sib sisters fed with E. europaeus . We did not find this in the reciprocal cross. However, still more than half of the egg masses are deposited on E. europaeus by hybrids that have no experience on this host. We conclude that the semi-dominant character of acceptance of E. europaeus and a tendency of Rosaceae-feeding Yponomeuta to deposit egg masses on this host may have created the opportunity for the host shift of the predecessor of Y. cagnagellus from Rosaceae to the Celastraceae. This shift may have been further facilitated by a weak tendency of adults to oviposit on their larval food source.
Host Races and Sympatric Speciation in Small Ermine Moths, Yponomeutidae
Entomologia Experimentalis et Applicata, 1981
The amount of genetic differentiation at various levels of evolutionary divergence (conspecific populations, sibling species and non-sibling Species) in Yponomeuta was determined. Genetic distances between siblings or non-siblings were found to cover a wide range. It is concluded that such estimates do not give much information on the speciation process itself. Inbreeding coefficients were calculated for populations of Y. padellus from a total of six host plants. The grand mean FSTvalue is 0.030 + 0.012. FSTvalues for populations sampled from Crataegus, the common food plant of Y. padellus, are 2-3.5 times smaller than those for populations from the other food plants taken together. Host race formation, as measured by significant differences in allozyme frequencies between sympatric populations on two or more food plants, was investigated in four areas. Host race formation seems to occur in Y. padellus and sympatric speciation is a likely event.
Pattern and process in the evolution of insect-plant associations: Yponomeuta as an example
Entomologia Experimentalis et Applicata, 1996
Phylogenetic studies are increasing our understanding of the evolution of associations between phytophagous insects and their host plants. Sequential evolution, i.e. the shift of insect herbivores onto pre-existing plant species, appears to be much more common than coevolution, where reciprocal selection between interacting insects and plants is thought to induce chemical diversification and resistance in plants and food specialization in insects. Extreme host specificity is common in phytophagous insects and future studies are likely to reveal even more specialization. Hypotheses that assume that food specialists have selective advantages over generalists do not seem to provide a general explanation for the ubiquity of specialist insect herbivores. Specialists are probably committed to remain so, because they have little evolutionary opportunity to reverse the process due to genetically determined constraints on the evolution of their physiology or nervous system. The same constraints might result in phylogenetic conservatism, i.e. the frequent association of related insect herbivores with related plants. Current phylogenetic evidence, however, indicates that there is no intrinsic direction to the evolution of specialization. Historical aspects of insect-host plant associations will be illustrated with the small ermine moth genus Yponomeuta. Small ermine moths show an ancestral host association with the family Celastraceae. The genus seems to be committed to specialization per se rather than to a particular group of plants. Whatever host shift they have made in their evolutionary past (onto Rosaceae, Crassulaceae, and Salicaceae), they remain monophagous. The oligophagous Y. padellus is the only exception. This species might comprise a mosaic of genetically divergent host-associated populations.
Oviposition in Yponomeuta cagnagellus: the importance of contact cues for host plant acceptance
Physiological Entomology, 1999
Small ermine moths (Yponomeutidae: Lepidoptera) are specialist herbivores. Species within the genus Yponomeuta are each specialized on a limited number of plant species, mainly within genera belonging to the Celastraceae. European Yponomeuta species have developed new specialized host af®liations, mainly on rosaceous hosts. Since these host shifts are reputed to be of consequence for speciation, the role of the ovipositing female is of particular interest. Study of the pre-oviposition behaviour of gravid Y. cagnagellus (Hb.) moths on host (Euonymus europaeus), non-host (Crateagus monogyna) and arti®cial oviposition substrates, provided information on the nature of the cues used for host plant acceptance and the insect's perception of these cues. Host selection by adult females occurs with contact chemoreceptors probably located on the antennae or tarsi. MeOH-soluble, non-volatile phytochemical compounds washed from the host plant's surface and applied on an arti®cial twig are suf®cient to stimulate a complete sequence of behavioural elements leading to oviposition. Volatiles do not have a large effect on the pre-oviposition behaviour.
Ecological Entomology, 2000
1. A series of experiments was conducted to measure the impact of plant genotype, plant growth rate, and intraspeci®c competition on the oviposition preference and offspring performance of the host races of Eurosta solidaginis (Diptera: Tephritidae), a¯y that forms galls on Solidago altissima and Solidago gigantea (Asteraceae). Previous research has shown that both host races prefer to oviposit on their own host plant where survival is much higher than on the alternate host plant. In this study, neither host race showed any relationship between oviposition preference and offspring performance in choosing among plants of their natal host species.
Genetic architecture of host specialisation in Yponomeuta
2014
Host shifts can trigger ecological speciation in herbivorous insects. The probability of a successful host shift is a function of the genetic complexity underlying the traits defining host use. Host use includes at least three components: adult and larval acceptance and larval performance. European species of Yponomeuta are highly specialised on species of different plant families. One of these specialists, Yponomeuta cagnagellus, originated from an ancestor specialised on Rosaceae, but has shifted to Celastraceae. Its close relative, Y. padellus, is associated with Rosaceous hosts. We studied the inheritance of host use traits on their interspecific hybrids. We conclude that adult host acceptance, larval host acceptance and larval performance are inherited independently. Larval survival involves multiple genes. It seems that the architecture of host use is defined by species-specific, co-adapted combinations of alleles. Second generation hybrids survive when F1 is crossed back to o...
Biological Journal of the Linnean Society, 2013
Divergent host preference (i.e. host fidelity) plays a significant role in the speciation process in phytophagous insects. However, how and to what extent this divergence reduces gene flow between populations has rarely been measured. Here, we estimated the intensity of assortative mating caused solely by host fidelity in two host races of the phytophagous ladybird beetle Henosepilachna diekei, specialized on Mikania micrantha (Asteraceae) and Leucas lavandulifolia (Lamiaceae) in West Java, Indonesia. These host races mated randomly in the absence of host plants under laboratory conditions, but demonstrated nearly complete assortative mating in field cages with the two host plants, by spending almost all of their time on their respective host plants. The frequency of assortative mating in the field cages was not affected drastically by host plant patch structure. These results suggest that fidelity to the different host plants yields directly almost complete reproductive isolation between the host races by limiting the habitat on the respective host plant. In addition, the high host fidelity also ensures female oviposition on the original host plant. As larvae cannot survive on non-host plants, a positive association between female oviposition preference and larval performance on the host plant on which the beetles are specialized will further facilitate the evolution of host fidelity.
Biological Journal of the Linnean Society, 2000
Temporal changes in allele frequencies were studied in host-associated populations of the small rrmine rnoth 2jotfo7~z~utn padellu~. At one site, populations from three host plants ! , Y o r h auruparin, Amelotichier laniorckii, and Crataegus spp.) were sampled annually during a four-yrarperiod and analysed \\rith 20 polJmorphic allozyme markers. At t\vo other sites, allele frcquencirs at 5-6 enzynir loci of 1: paddlm populations from two different host plants were also tested for consistency over a 13-year-period, Significant allele frequenc); changes occurred in the short-term analysis, whereas allele frcquencies remained relatively stable through time in the long-term analyars. Furthermore, allele frequencies of 1: padellus populations from L'mtmgus spp. were relatively stable comparrd to the other host populations. The role of the agents responsible for the obseiyed patterns is discussed. 0 ?OOO The 1.innran Socien or Londoi~ ADDITIONAL KEY WORDS:-alloz)me Imkitiontemporal genetic change insect-plant interactionsgenetic population structure.
Insects, 2019
Recently in Poland, cases of host expansion have frequently been observed in the typically monophagous bird-cherry ermine moth (Yponomeuta evonymella), which has moved from its native host plant, bird cherry (Prunus padus), to a new, widely distributed plant that is invasive in Europe, black cherry (P. serotina). We attempted to verify the reasons behind this host change in the context of the enemy-free space hypothesis by focusing on parasitoids attacking larval Y. evonymella on one of three host plant variants: The primary host, P. padus; initially P. padus and later P. serotina (P. padus/P. serotina); or the new host, P. serotina. This experiment investigated if changing the host plant could be beneficial to Y. evonymella in terms of escaping from harmful parasitoids and improving survival rate. We identified nine species of parasitoids that attack larval Y. evonymella, and we found that the number of parasitoid species showed a downward trend from the primary host plant to the P...