Biology subjects

Obrycki, J. J.

Publications and source records attributed to Obrycki, J. J..

3 recordsLinked to original sources

bioRxiv2023

Shared patterns of population genomic variation and phenotypic response across rapid range expansions in two invasive lady beetle species

Non-native lady beetle species have often been introduced, with variable success, into North America for biological control of aphids, scales, whiteflies, and other agricultural pests. Two predatory lady beetle species, Propylea quatuordecimpunctata and Hippodamia variegata, both originating from Eurasia, were first discovered near Montreal, Quebec, in North America in 1968 and 1984, respectively, and have since expanded into northeastern North America and the midwestern United States. In this study, we estimate the range-wide population structure, establishment and range-expansion, and recent evolutionary history of these species of non-native lady beetles using reduced representation genotyping-by-sequencing via ddRADseq. In addition, we quantified the responses to a key abiotic factor, photoperiod, that regulates adult reproductive diapause in these two species and may influence their latitudinal distribution and spread in North America. Our analyses detect (1) non-significant genetic differentiation and divergence among North American populations, (2) evidence of reduced contemporary gene flow within the continental US, (3) significant phenotypic differences in diapause induction despite genetic similarities across sampled populations.

evolutionary biology↗

bioRxiv2022

Like mother, like daughter? Phenotypic plasticity, environmental covariation, and heritability of size in a parthenogenetic wasp

Dinocampus coccinellae (Hymenoptera:Braconidae, Euphorinae) is a solitary, generalist Braconid parasitoid wasp that reproduces through thelytokous parthenogenesis, an asexual process in which diploid daughters emerge from unfertilized eggs, and parasitizes over fifty diverse species of coccinellid ladybeetles worldwide as hosts. Here we utilized a common garden and reciprocal transplant experiment using parthenogenetic lines of D. coccinellae presented with three different host ladybeetle species of varying sizes, across multiple generations to investigate heritability, plasticity, and environmental covariation of body size in D. coccinellae. We expected positively correlated parent-offspring parasitoid regressions, indicative of heritable size variation, from unilineal (parent and offspring reared on same host species) lines, since these restrict environmental variation in phenotypes. In contrast, because multilineal (parent and offspring reared on different host species) lines would induce phenotypic plasticity of clones reared in varying environments, we expected negatively correlated parent-offspring parasitoid regressions. Our results indicate (1) little heritable variation in body size, (2) strong independence of offspring size on the host environment, (3) a consistent signal of size-host tradeoff wherein small mothers produced larger offspring, and vice versa, independent of host environment. We then model the evolution of size and host-shifting under a constrained fecundity advantage model of Copes Law using a Hidden Markov Model, showing that D. coccinellae likely has considerable fitness advantage to maintain phenotypic plasticity in body size despite parthenogenetic reproduction.

evolutionary biology↗

bioRxiv2021

Genome of the parasitoid wasp Dinocampus coccinellae reveals extensive duplications, accelerated evolution, and independent origins of thelytokous parthenogeny and solitary behavior

Dinocampus coccinellae (Hymenoptera: Braconidae) is a generalist parasitoid wasp that parasitizes >50 species of predatory lady beetles (Coleoptera: Coccinellidae), with thelytokous parthenogeny as its primary mode of reproduction. Here we present the first high quality genome of D. coccinellae using a combination of short and long read sequencing technologies, followed by assembly and scaffolding of chromosomal segments using Chicago+ HiC technologies. We also present a first-pass ab initio genome annotation, and resolve timings of divergence and evolution of (1) solitary behavior vs eusociality, (2) arrhenotokous vs thelytokous parthenogenesis, and (3) rates of gene loss and gain among Hymenopteran lineages. Our study finds (1) at least two independent origins of eusociality and solitary behavior among Hymenoptera, (2) two independent origins of thelytokous parthenogenesis from ancestral arrhenotoky, and (3) accelerated rates of gene duplications, loss, and gain along the lineages leading to D. coccinellae. Our work both affirms the ancient divergence of Braconid wasps from ancestral Hymenopterans and accelerated rates of evolution in response to adaptations to novel hosts, including polyDNA viral co-evolution.

genomics↗