1,721,049 research outputs found
Genetic diversity in populations of asexual and sexual bag worm moths (Lepidoptera: Psychidae).
Full text linkDespite the two-fold cost of sex, most of the higher animals reproduce
sexually. The advantage of sex has been suggested to be its ability,
through recombination, to generate greater genetic diversity than
asexuality, thus enhancing adaptation in a changing environment. We
studied the genetic diversity and the population structure of three
closely related species of bag worm moths: two strictly sexual (Dahlica
charlottae and Siederia rupicolella) and one strictly asexual (D.
fennicella). These species compete for the same resources and share the
same parasitoids. Allelic richness was comparable between the sexual
species but it was higher than in the asexual species. All species
showed high heterozygote deficiency and a large variation was observed
among FIS values across loci and populations. Large genetic
differentiation was observed between populations confirming the poor
dispersal ability of these species. The asexual species showed lower
genotype diversity than the sexual species. Nevertheless, genotype
diversity was high in all asexual populations. The three different
species show a similar population structure characterised by high
genetic differentiation among populations and low dispersal. Most of the
populations showed high heterozygote deficiency likely due to the
presence of null alleles at most of the loci and/or to the Wahlund
effect. Although the parthenogenetic D. fennicella shows reduced genetic
diversity compared to the sexual species, it still shows surprisingly
high genotype diversity. While we can not totally rule out the presence
of cryptic sex, would explain this high genotype diversity, we never
observed sex in the parthenogenetic D. fennicella, nor was there any
other evidence of this. Alternatively, a non-clonal parthenogenetic
reproduction, such as automictic thelytoky, could explain the high
genotypic diversity observed in D. fennicella
Parasites and sexual reproduction in psychid moths
No full textPersistence of sexual reproduction among coexisting asexual competitors
has been a major paradox in evolutionary biology. The number of
empirical studies is still very limited, as few systems with coexisting
sexual and strictly asexual lineages have been found. We studied the
ecological mechanisms behind the simultaneous coexistence of a sexually
and an asexually reproducing closely related species of psychid moth in
Central Finland between 1999 and 2001. The two species compete for the
same resources and are often infected by the same hymenopteran
parasitoids. They are extremely morphologically and behaviorally similar
and can be separated only by their reproductive strategy (sexual vs.
asexual) or by genetic markers. We compared the life-history traits of
these species in two locations where they coexist to test predictions of
the cost-of-sex hypothesis. We did not find any difference in female
size, number of larvae, or offspring survival between the sexuals and
asexuals, indicating that sexuals are subject to cost of sex. We also
used genetic markers to check and exclude the possibility of Wolbachia
bacteria infection inducing parthenogenesis. None of the samples was
infected by Wolbachia and, thus, it is unlikely that these bacteria
could affect our results. We sampled 38 locations to study the
prevalence of parasitoids and the moths' reproductive strategy. We found
a strong positive correlation between prevalence of sexual reproduction
and prevalence of parasitoids. In locations where parasitoids are rare
asexuals exist in high densities, whereas in locations with a high
parasitoid load the sexual species was dominant. Spatial distribution
alone does not explain the results. We suggest that the parasite
hypothesis for sex may offer an explanation for the persistence of
sexual moths in this system
Data from 'Testing the direct and genetic benefit hypotheses of polyandry in the wood tiger moth’ Santostefano F, Galarza JA, Mappes J, BEAS 2018
No full textData from 'Testing the direct and genetic benefit hypotheses of polyandry in the wood tiger moth’ Santostefano F, Galarza JA, Mappes J, BEAS 2018Contains two xlsx datasets and associated readme file<br
Phylogeny and evolution of parthenogenesis in Finnish bagworm moth species (Lepidoptera : Psychidae : Naryciinae) based on mtDNA-markers
No full textWe investigated species diversity and evolution of parthenogenesis among
bagworm moth species of Dahlica and Siederia using mitochondrial DNA
sequencing. Parthenogenesis is rare among Lepidoptera other than
Psychidae. Genera Dahlica and Siederia form a confusing group with
controversial species boundaries and widely overlapping morphological
features that make species determination difficult. We evaluated the
reliability of species determination based on wing scale morphology by
comparing it with a phylogenetic tree obtained using mtDNA. Species
determination based on morphological characteristics did not correspond
to species determination based on mtDNA markers. On the basis of the
molecular phylogeny, the status of these two genera is questionable. Our
results indicate that parthenogenetic D. fennicella, D. triquetrella and
D. lichenella evolved independently from different sexual ancestors
suggesting that asexual reproduction is favoured in this group
Influence of male mating history on female reproductive success among monandrous Naryciinae (Lepidoptera: Psychidae)
No full text1. Multiple male copulations can have detrimental effects on female fitness
due to sperm limitation. 2. Monandrous Naryciinae females are immobile while the males are
short-lived and do not feed. Multiple male mating is therefore expected
to lead to sperm limitation in females. Sperm limitation and male
limitation are hypothesised as causes of the repeated evolution of
parthenogenetic reproduction in the Psychidae.
3. In this study, the effects of multiple male mating on female
reproduction are investigated in several species of Naryciinae by
allowing males multiple copulations. The results for two species,
Siederia listerella and Dahlica lichenella, are compared. The sex ratios
of 53 natural populations are examined for indications of male
limitation.
4. Previous copulations by the male increased the female's risk of
remaining unfertilised. However, contrary to expectations, those
unfertilised females were capable of successful re-mating.
5. In S. listerella, the number of previous copulations of males
negatively influenced female fitness. Females produced 30% fewer
offspring if they mated with a previously mated male. In D. lichenella,
the older the male and the lower its number of total lifetime
copulations, the higher the female's reproductive success.
6. Only a fraction of the investigated populations had a female-skewed
sex ratio, but differences in development time between males and females
could lead to reproductive asynchrony.
7. In conclusion, male mating history did not lead to strong sperm
limitation in Naryciinae as had been suggested by their life history
Quantitative genetic approach for assessing invasiveness: geographic and genetic variation in life-history traits
No full textPredicting the spread of invasive species is a challenge for modern
ecology. Although many invasive species undergo genetic bottlenecks
during introduction to new areas resulting in a loss of genetic
diversity, successful invaders manage to flourish in novel environments
either because of pre-adaptations or because important traits contain
adaptive variation enabling rapid adaptation to changing conditions. To
predict and understand invasion success, it is crucial to analyse these
features. We assessed the potential of a well-known invader, the
Colorado potato beetle (Leptinotarsa decemlineata), to expand north of
its current range in Europe. A short growing season and harsh
overwintering conditions are apparent limiting factors for this species'
range. By rearing full-sib families from four geographically distinct
populations (Russia, Estonia, Poland, Italy) at two fluctuating
temperature regimes, we investigated (a) possible differences in
survival, development time, and body size among populations and (b) the
amount of adaptive variation within populations in these traits. All
populations were able to complete their development in cooler conditions
than in their current range. A significant genotype-environment
interaction for development time and body size suggests the presence of
adaptive genetic variation, indicating potential to adapt to cooler
conditions. The northernmost population had the highest survival rates
and fastest development times on both temperature regimes, suggesting
pre-adaptation to cooler temperatures. Other populations had minor
differences in development times. Interestingly, this species lacks the
classical trade-off between body size and development time which could
have contributed to its invasion potential. This study demonstrates the
importance of considering both ecological and evolutionary aspects when
assessing invasion risk
The voyage of an invasive species across continents: genetic diversity of North American and European Colorado potato beetle populations
No full textThe paradox of successful invading species is that they are likely to be
genetically depauperate compared to their source population. This study
on Colorado potato beetles is one of the few studies of the genetic
consequences of continent-scale invasion in an insect pest.
Understanding gene flow, population structure and the potential for
rapid evolution in native and invasive populations offers insights both
into the dynamics of small populations that become successful invaders
and for their management as pests. We used this approach to investigate
the invasion of the Colorado potato beetle (Leptinotarsa decemlineata)
from North America to Europe. The beetles invaded Europe at the
beginning of the 20th century and expanded almost throughout the
continent in about 30 years. From the analysis of mitochondrial DNA
(mtDNA) and amplified fragment length polymorphism (AFLP) markers, we
found the highest genetic diversity in beetle populations from the
central United States. The European populations clearly contained only a
fraction of the genetic variability observed in North American
populations. European populations show a significant reduction at
nuclear markers (AFLPs) and are fixed for one mitochondrial haplotype,
suggesting a single successful founder event. Despite the high vagility
of the species and the reduction of genetic diversity in Europe, we
found a similar, high level of population structure and low gene flow
among populations on both continents. Founder events during range
expansion, agricultural management with crop rotation, and selection due
to insecticide applications are most likely the causes partitioning
genetic diversity in this species
Cold tolerance during larval development: effects on the thermal distribution limits of Leptinotarsa decemlineata
No full textInsects' cold tolerance during their development is a surprisingly
understudied subject in ecology, despite the fact that subzero
temperatures during the growing season are common at high altitudes and
latitudes. Subzero temperatures can have detrimental effects on
organisms, restricting a species' range. This study addresses the
question whether night frosts during the growing season have an instant
or delayed negative impact on larval mortality of the Colorado potato
beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae). We
also tested whether populations from the centre (Poland) and margins
(Russia) of the distribution range of L. decemlineata differ in their
responses to subzero exposure and a low rearing temperature. Larvae of
three ages were subjected to a subzero temperature (-4 degrees C for 3 h
simulating night frost) twice, after which they were reared on a
fluctuating temperature regime of 10-15 degrees C. These rearing
conditions imitated cool summer temperatures beyond the beetles' current
range, such as in Finland. Individuals of both populations were highly
cold tolerant, as only 3.1% of larvae died immediately following the
subzero treatment. Nonetheless, the low rearing temperature was harmful
to beetles of both populations. It caused high larval (ca. 90%) and
overwintering (ca. 80%) mortality. As beetle performance was affected
solely by rearing temperature, low temperatures during the growing
season rather than night frosts apparently retard the beetle's northern
expansion
Investigating the origin of parthenogenesis and ploidy level in Dahlica fennicella (Lepidoptera: Psychidae)
No full textThe theories for the predominance of sexual reproduction predict that parthenogens should have no long-term evolutionary potential due to the lack of genetic recombination, despite short term advantages. Although parthenogenesis is rare among high order animals, true parthenogens can be found in various taxa. The intriguing question of the proliferation and persistence of parthenogenetic species needs investigation. An ideal species for such research is a parthenogenetic mont Dahlica fennicella that appears to be as equally successful as other coexisting sexual species. We investigated whether high ploidy level of D. fennnicella is due to hybridization between closely related sexual species. The results form flow cytometry measurements confirmed that D. fennicella is exclusively tetraploid whereas all sexual species of the genera Dahlica and Siederia are diploid. Our phylogenentic results showed the non-hybrid origin of the parthenogenetic D. fennicella in this group of Lepidoptera. Most likely, the parthenogenetic D. fennicella orginated by autopolyploidization of D. lazuri, which is one of its closely related sexual species. We suggest that the apparent evolutionary success of D. fennicella might be due to polyploidy that could mask deleterious mutuations and probide greater levels of genetic variations.peerReviewe
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