Genetic Mechanisms of Pollution Resistance in a Marine Invertebrate

Galletly, Bronwyn C.; Blows, Mark W.; Marshall, Dustin J.

doi:10.1890/06-2079.1

Cited by 39 publications

(39 citation statements)

References 45 publications

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“…Previous studies have detected similar patterns, finding that environmental stress reduces additive genetic variance (Bubliy & Loeschcke, 2002; Galletly et al., 2007) and increases nonadditive genetic variance (Blows & Sokolowski, 1995; Jinks, Jean, & Pooni, 1973). However, other studies have found stress to have the opposite effect, or little effect at all (Hoffmann & Parsons, 1991; Pakkasmaa, Merila, & O'Hara, 2003).…”

Section: Discussionmentioning

confidence: 99%

“…For many marine organisms, therefore, survival at this early stage of the life cycle will be a critical bottleneck in the persistence of future populations. Galeolaria 's free‐spawning nature also makes it ideal for exploring larval vulnerability to environmental stress using cross‐classified breeding designs, whereby the subdivision of ejaculates and egg clutches allows males to be mated with multiple females and vice versa (Galletly, Blows, & Marshall, 2007; Munday et al., 2013). Using such a design, we decomposed phenotypic variance in larval survival within and across thermal environments into its nonadditive genetic and maternal environmental components (partitioned from additive genetic effects; see Chirgwin, Monro, Sgro, & Marshall, 2015).…”

Section: Introductionmentioning

confidence: 99%

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The other 96%: Can neglected sources of fitness variation offer new insights into adaptation to global change?

Chirgwin

Marshall

Sgrò

et al. 2016

Evolutionary Applications

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Mounting research considers whether populations may adapt to global change based on additive genetic variance in fitness. Yet selection acts on phenotypes, not additive genetic variance alone, meaning that persistence and evolutionary potential in the near term, at least, may be influenced by other sources of fitness variation, including nonadditive genetic and maternal environmental effects. The fitness consequences of these effects, and their environmental sensitivity, are largely unknown. Here, applying a quantitative genetic breeding design to an ecologically important marine tubeworm, we examined nonadditive genetic and maternal environmental effects on fitness (larval survival) across three thermal environments. We found that these effects are nontrivial and environment dependent, explaining at least 44% of all parentally derived effects on survival at any temperature and 96% of parental effects at the most stressful temperature. Unlike maternal environmental effects, which manifested at the latter temperature only, nonadditive genetic effects were consistently significant and covaried positively across temperatures (i.e., parental combinations that enhanced survival at one temperature also enhanced survival at elevated temperatures). Thus, while nonadditive genetic and maternal environmental effects have long been neglected because their evolutionary consequences are complex, unpredictable, or seen as transient, we argue that they warrant further attention in a rapidly warming world.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The other 96%: Can neglected sources of fitness variation offer new insights into adaptation to global change?

Chirgwin

Marshall

Sgrò

et al. 2016

Evolutionary Applications

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“…Styela plicata is a broadcast spawning, solitary ascidian and a simultaneous hermaphrodite (although self-sterile) (65). S. plicata is thought to be invasive to eastern Australia, is common on made-made structures (growing both in isolation and in clumps), and in vitro fertilization by strip-spawning techniques is straightforward (66). Adult S. plicata were collected and field manipulations conducted at Manly Boat Harbor (Brisbane, Australia; 27.467 E 153.183 S).…”

Section: Methodsmentioning

confidence: 99%

“…This procedure allowed the eggs to be retained inside the filter, whereas the sperm passed through into the beaker. Where eggs were required for fertilization experiments, we briefly soaked them in 0.5 M potassium chloride to kill any remaining sperm (66).…”

Section: Methodsmentioning

confidence: 99%

“…To create 4 sperm concentration treatments (per adult density treatment), we serially diluted the sperm extract to 100%, 10%, 1%, and 0.1% of the original extraction. We added each sperm treatment to the egg samples in 3 0.5-ml doses at 5-min intervals-a standard procedure to allow time for polyspermy blocks to form (42,66). After 1 h we estimated fertilization success by scoring cleaved and uncleaved eggs (as described in ''Sperm longevity'').…”

Section: Methodsmentioning

confidence: 99%

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Gamete plasticity in a broadcast spawning marine invertebrate

Crean

Marshall

2008

Proc. Natl. Acad. Sci. U.S.A.

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Sperm competition has classically been thought to maintain anisogamy (large eggs and smaller sperm) because males are thought to maximize their chance of winning fertilizations by trading sperm size for number. More recently it has been recognized that sperm quality (e.g., size, velocity) can also influence sperm competition, although studies have yielded conflicting results. Because sex evolved in the sea, debate has continued over the role of sperm competition and sperm environment in determining both sperm and egg size in externally fertilizing broadcast spawners. Remarkably, however, there have been no direct tests of whether broadcast spawners change the traits of their gametes depending on the likelihood of sperm competition. We manipulated the density (and thus, sperm environment) of a broadcast spawning ascidian (Styela plicata) in the field and then determined whether the phenotype of eggs and sperm changed. We found that sperm from adults kept at high density were larger and more motile than sperm from low-density adults. In vitro fertilizations revealed that sperm from high-density adults also lived longer and induced less polyspermy. Adult density also affected egg traits: eggs from high-density adults were smaller targets for sperm overall but produced larger ovicells than eggs from low-density adults. This suggests that broadcast spawning mothers balance (potentially conflicting) pre-and postzygotic selection pressures on egg size. Overall, our results suggest that sperm competition does not represent a strong force maintaining anisogamy in broadcast spawners. Instead, sperm limitation seems to select for large eggs and smaller, more numerous sperm.anisogamy ͉ sperm competition ͉ adaptive maternal effect ͉ transgenerational plasticity T he fundamental difference between the sexes is that males produce numerous, tiny sperm, and females produce relatively fewer, large eggs (anisogamy). Classic theory suggests that anisogamy most likely evolved by, and is maintained through, sperm competition (whereby sperm from 2 or more males compete to fertilize an egg) because males producing a greater number of sperm have a competitive advantage (refs. 1 and 2; but see ref. 3 for an alternative). In species with internal fertilization, competition for fertilizations can therefore be viewed as a ''raffle,'' whereby males that have the highest representation of sperm in the pool have the greatest chance of fertilizing eggs (4, 5). More recently, however, it has been proposed that sperm quality (e.g., sperm size, velocity, and longevity) can also influence the outcome of sperm competition (6, 7). Furthermore, because a male's sperm supply is limited (8, 9) and each mating opportunity may carry a variable risk of sperm competition (10), males must make decisions on the optimal allocation of both sperm number and quality for each mating event. The optimal allocation of sperm size and number within an ejaculate remains a source of intense debate (reviewed in refs. 7 and 9).The prediction that males should increase the ...

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Using clones and copper to resolve the genetic architecture of metal tolerance in a marine invader

McKenzie

Johnston

Brooks

2012

Ecology and Evolution

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The global spread of invasive species may be facilitated by adaptation to the practices that humans use to manage those species. For example, marine invertebrates that adapt to metal-based antifouling biocides on ship hulls may be more likely to be introduced to and establish in metal-polluted environments. We tested this idea by studying clonal variation in tolerance to, and ability to recover from, exposure to copper in a widespread invasive marine bryozoan, Watersipora subtorquata. We cloned colonies of this organism to independently test multiple environments in a genotype by environment design, and then created a genetic variance–covariance matrix. Genotypes were exposed to a gradient of copper concentrations and growth measured during exposure and after a recovery period. There was a significant genotype × environment interaction in growth during exposure and recovery. We found clonal variation in tolerance and ability to recover from exposure to copper, with growth during exposure apparently trading off against growth after exposure. A weak genetic correlation between growth during and after exposure further indicated that they are separate traits. Overall, the genetic variation within this population indicates that there is considerable potential for adaptation to copper, but this comes at a cost to growth in unpolluted environments.

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Genetic Mechanisms of Pollution Resistance in a Marine Invertebrate

Cited by 39 publications

References 45 publications

The other 96%: Can neglected sources of fitness variation offer new insights into adaptation to global change?

The other 96%: Can neglected sources of fitness variation offer new insights into adaptation to global change?

Gamete plasticity in a broadcast spawning marine invertebrate

Using clones and copper to resolve the genetic architecture of metal tolerance in a marine invader

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