scholarly journals Plasticity and Artificial Selection for Developmental Mode in a Poecilogonous Sea Slug

2020 ◽  
Author(s):  
Serena A. Caplins

AbstractDevelopmental mode describes the means by which larvae are provisioned with the nutrients they need to proceed through development and typically results in a trade-off between offspring size and number. The sacoglossan sea slug Alderia willowi exhibits intraspecific variation for developmental mode (= poecilogony) that is environmentally modulated with populations producing more yolk-feeding (lecithotrophic) larvae during the summer, and more planktonic feeding (planktotrophic) larvae in the winter. I found significant family level variation in the reaction norms between 17 maternal families of A. willowi when reared in low (16 ppt) versus high (32 ppt) salinity. I documented a significant response to selection for lecithotrophic larvae, the proportion of which increased 32% after three generations of selection in high salinity, and 18% after 2 generations in low salinity (realized heritability: 0.365 ± 0.024). The slope of the reaction norm was maintained following one generation of selection for lecithotrophy and one generation of selfing. The rapid response to selection favoring one developmental mode may speak to the rarity of intraspecific variation for developmental mode, which could fix for one mode over another much more readily than has generally been assumed from studies of less plastic organisms.

2020 ◽  
Author(s):  
Henry Goehlich ◽  
Linda Sartoris ◽  
Kim Sara Wagner ◽  
Carolin C. Wendling ◽  
Olivia Roth

AbstractGenetic adaptation and phenotypic plasticity facilitate the invasion of new habitats and enable organisms to cope with a rapidly changing environment. In contrast to genetic adaptation that spans multiple generations as an evolutionary process, phenotypic plasticity allows acclimation within the life-time of an organism. Genetic adaptation and phenotypic plasticity are usually studied in isolation, however, only by including their interactive impact, we can understand acclimation and adaptation in nature. We aimed to explore the contribution of adaptation and plasticity in coping with an abiotic (salinity) and a biotic (Vibrio bacteria) stressor using six different populations of the broad-nosed pipefish Syngnathus typhle that originated from either high or low saline environments. We hypothesized that wild S. typhle populations are locally adapted to the salinity and prevailing pathogens of their native environment, and that short-term acclimation of parents to a novel salinity may aid in buffering offspring phenotypes in a matching environment. To test these hypotheses, we exposed all wild caught animals, to either high or low salinity, representing native and novel salinity conditions and allowed animals to mate. After male pregnancy, offspring was split and each half was exposed to one of the two salinities and infected with Vibrio alginolyticus bacteria that were evolved at either of the two salinities in a fully reciprocal design. We investigated life history traits of fathers (offspring survival, offspring size) and expression of 47 target genes in mothers and offspring.Pregnant males originating from high salinity exposed to low salinity were highly susceptible to opportunistic fungi infections resulting in decreased offspring size and number. In contrast, no signs of fungal infection were identified in fathers originating from low saline conditions suggesting that genetic adaptation has the potential to overcome the challenging conditions of low salinity. Genetic adaptation increased survival rates of juveniles from parents in lower salinity (in contrast to those from high salinity). Juvenile gene expression indicated patterns of local adaptation, trans-generational plasticity and developmental plasticity. The results of our study suggest that pipefish locally adapted to low salinity retain phenotypic plasticity, which allows them to also cope with ancestral salinity levels and prevailing pathogens.


2002 ◽  
Vol 80 (10) ◽  
pp. 2566 ◽  
Author(s):  
J. Estany ◽  
D. Villalba ◽  
M. Tor ◽  
D. Cubiló ◽  
J. L. Noguera

2001 ◽  
Vol 55 (1) ◽  
pp. 66-76 ◽  
Author(s):  
Roger Byrne ◽  
B. Lynn Ingram ◽  
Scott Starratt ◽  
Frances Malamud-Roam ◽  
Joshua N. Collins ◽  
...  

AbstractAnalysis of diatoms, pollen, and the carbon-isotopic composition of a sediment core from a brackish marsh in the northern part of the San Francisco Estuary has provided a paleosalinity record that covers the past 3000 yr. Changes in marsh composition and diatom frequencies are assumed to represent variations in freshwater inflow to the estuary. Three periods of relatively high salinity (low freshwater inflow) are indicated, 3000 to 2500 cal yr B.P., 1700 to 730 cal yr B.P., and ca. A.D. 1930 to the present. The most recent period of high salinity is primarily due to upstream storage and water diversion within the Sacramento–San Joaquin watershed, although drought may also have been a factor. The two earlier high-salinity periods are likely the result of reduced precipitation. Low salinity (high freshwater flow) is indicated for the period 750 cal yr B.P. to A.D. 1930.


1981 ◽  
Vol 31 (4) ◽  
pp. 426-432 ◽  
Author(s):  
Sampo Sirkkomaa ◽  
Ulf B. Lindström

2019 ◽  
Vol 70 (4) ◽  
pp. 541 ◽  
Author(s):  
Martha J. Zapata ◽  
S. Mažeika P. Sullivan

Variability in the density and distribution of adult aquatic insects is an important factor mediating aquatic-to-terrestrial nutritional subsidies in freshwater ecosystems, yet less is understood about insect-facilitated subsidy dynamics in estuaries. We surveyed emergent (i.e. adult) aquatic insects and nearshore orb-weaving spiders of the families Tetragnathidae and Araneidae in a subtropical estuary of Florida (USA). Emergent insect community composition varied seasonally and spatially; densities were lower at high- than low-salinity sites. At high-salinity sites, emergent insects exhibited lower dispersal ability and a higher prevalence of univoltinism than low- and mid-salinity assemblages. Orb-weaving spider density most strongly tracked emergent insect density rates at low- and mid-salinity sites. Tetragnatha body condition was 96% higher at high-salinity sites than at low-salinity sites. Our findings contribute to our understanding of aquatic insect communities in estuarine ecosystems and indicate that aquatic insects may provide important nutritional subsidies to riparian consumers despite their depressed abundance and diversity compared with freshwater ecosystems.


Aquaculture ◽  
2014 ◽  
Vol 430 ◽  
pp. 159-165 ◽  
Author(s):  
Hugues de Verdal ◽  
Westly Rosario ◽  
Marc Vandeputte ◽  
Nerafe Muyalde ◽  
Pierre Morissens ◽  
...  

2013 ◽  
Vol 9 (5) ◽  
pp. 20130327 ◽  
Author(s):  
Matthew Schrader ◽  
Rebecca C. Fuller ◽  
Joseph Travis

Crosses between populations or species often display an asymmetry in the fitness of reciprocal F 1 hybrids. This pattern, referred to as isolation asymmetry or Darwin's Corollary to Haldane's Rule, has been observed in taxa from plants to vertebrates, yet we still know little about which factors determine its magnitude and direction. Here, we show that differences in offspring size predict the direction of isolation asymmetry observed in crosses between populations of a placental fish, Heterandria formosa . In crosses between populations with differences in offspring size, high rates of hybrid inviability occur only when the mother is from a population characterized by small offspring. Crosses between populations that display similarly sized offspring, whether large or small, do not result in high levels of hybrid inviability in either direction. We suggest this asymmetric pattern of reproductive isolation is due to a disruption of parent–offspring coadaptation that emerges from selection for differently sized offspring in different populations.


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