Topic
Embiotoca
About: Embiotoca is a research topic. Over the lifetime, 8 publications have been published within this topic receiving 345 citations.
Papers
TL;DR: Embiotoca lateralis and E. jacksoni are very similar morphologically and exhibit the greatest dietary overlap within a guild of microcarnivorous subtidal reef fishes off Santa Barbara, California, but each species occupies all reef depths and commonly forages over both food substrates in allopatry.
Abstract: Embiotoca lateralis and E. jacksoni are very similar morphologically and exhibit the greatest dietary overlap within a guild of microcarnivorous subtidal reef fishes off Santa Barbara, California. Within this zone of sympatry, they segregate by depth: E. lateralis numerically dominates shallow reef areas covered by various algae, from which it picks its prey; E jacksoni dominates and forages over deeper areas covered by a relatively food-poor "turf" of sessile invertebrates and small algae. E. lateralis rarely fed from turf-covered substrates experimentally translocated from deep water, while E. jacksoni frequently fed from translocated shallow algae. In allopatry, however, each species occupies all reef depths and commonly forages over both food substrates. When E. lateralis was experimentally removed from a reef inhabited by both species, E. jacksoni entered shallow areas and foraged over algae. However, removing E. jacksoni from another reef did not affect the distribution of E. lateralis. E. lateralis aggressively dominated E. jacksoni, and E. jacksoni avoided foraging near E. lateralis. E. lateralis eventually entered and foraged over deep reef areas only when all shallow algae and E. jacksoni were removed. Sympatric population densities of E. lateralis, here at the southern margin of its geographical range, are much lower than those of allopatric populations elsewhere. Hence, shallow food sources may be sufficiently abundant that marginal E. lateralis populations occupy only this richest end of the bathymetric reef food gradient. This situation may provide a competitive refuge for E. jacksoni in less productive deep reef areas, thus maintaining the coexistence of these species within the same habitat.
175 citations
TL;DR: Two locally sympatric temperate marine reef fishes, Embiotoca jacksoni and E. lateralis (Embiotocidae), have high taxonomic similarity in diets, but differed considerably with respect to between-individual variability in taxonomic compositions of their diets.
Abstract: Two locally sympatric temperate marine reef fishes, Embiotoca jacksoni and E. lateralis (Embiotocidae), have high taxonomic similarity in diets. Subdivision of gammarid amphipods, their principal prey, was found. E. jacksoni took more tubicolous gammarid amphipods whereas E. lateralis consumed mostly free-living individuals. The species differed considerably with respect to between-individual variability in taxonomic compositions of their diets. Each E. jacksoni closely resembled other conspecifics in this regard while individual E. lateralis displayed very high between-fish variation. The principal interspecific difference in fish diets concerned the sizes of prey items taken. E. jacksoni ate small but very common items and the mean prey weight in their guts did not differ from random collections of available prey. E. lateralis concentrated on large, rarer sizes such that the average prey weight in their guts was much heavier than available or in the diet of E. jacksoni of the same length. Disparate foraging behaviors was a much better indicator of the relative differences in diets of these two fishes than was external fish morphology. E. jacksoni, which can winnow prey items from unwanted debris, was a relatively indiscriminant forager. E. lateralis did not winnow but actively searched for prey. This species was a much more discriminating forager, but displayed much variability in foraging behavior.
55 citations
TL;DR: Allopatric E. jacksoni displayed patterns of selectivity for prey of various sizes that were qualitatively different from those displayed by black surfperch sympatric with E. lateralis, and there was an apparant divergence in prey use by co-occurring Embiotoca species.
Abstract: Characteristics of the diet of black surfperch, Embiotoca jacksoni (Embiotocidae), were compared between islands where it occurs with and without a congener, the striped surfperch, Embiotoca lateralis. Several hypotheses were considered to explain observed dietary differences between allopatric and sympatric populations of black surfperch. Some differences could be readily attributed to interisland differences in the availability of prey items. Remaining dietary differences were examined in view of optimal foraging and competition hypotheses. Observations did not conform to predictions of optimal foraging theory, but did fit predictions regarding interspecific competition. There was a shift in the types and sizes of gammarid amphipods consumed between allpatric and sympatric populations of black surfperch. Gammarid amphipods are the most important prey taxon to both Embiotoca species, comprising more than 70% by number of all prey items in the diet. Further, allopatric E. jacksoni displayed patterns of selectivity for prey of various sizes that were qualitatively different from those displayed by black surfperch sympatric with E. lateralis. The prey size selectivity of allopatric black surfperch was qualitatively very similar to that found for E. lateralis. The differences in black surfperch diet that were not explained by differences in resource bases among islands were in the direction predicted by competition theory. The dietary breadth of E. jacksoni was also broader in allopatry than in sympatry. As a result of these dietary differences, there was an apparant divergence in prey use by co-occurring Embiotoca species.
42 citations
TL;DR: A combined phylogeographic and coalescent approach based on mitochondrial control region data shows that vicariance can only account for a portion of the observed divergences of the California surfperch species.
Abstract: With 18 closely related endemic species that radiated in a diversity of ecological niches, the California surfperches (Embiotocidae) species flock is a good candidate for the study of sympatric speciation. Resource partitioning has been suggested as an important driving force in the radiation of the surfperch family. Within the family, two congeneric sister species, Embiotoca jacksoni and E. lateralis, are known to compete strongly for a preferred single food resource and may be used as a model of ecological interactions for the family. Along the California coast, the distribution of the two species differs. Embiotoca jacksoni has a continuous range, whereas E. lateralis shows a disjunction with a distribution gap in the Southern California Bight. Two hypotheses may explain this disjunct distribution. Ecological competition may have displaced E. lateralis in favor of E. jacksoni. Alternatively, a common vicariant event may have separated the species into northern and southern populations, followed by secondary contact in E. jacksoni but not in E. lateralis. The two hypotheses predict different phylogeographic and demographic signatures. Using a combined phylogeographic and coalescent approach based on mitochondrial control region data, we show that vicariance can only account for a portion of the observed divergences. Our results are compatible with a significant role played by ecological competition in the southern range of the species.
41 citations
TL;DR: The striking similarity in the dynamics of multiple paternity in these species, when sampled in sympatry, may result from several alternative scenarios, including phylogenetic inertia, reproductive behaviour, and ecological competition.
Abstract: The black surfperch Embiotoca jacksoni and the striped surfperch E. lateralis (Embiotocidae, Perciformes) are livebearing temperate reef fishes that live sympatrically over a large portion of their distribution range, where they exhibit strong ecological competition. In order to assess whether mating strategies reflect competition, we investigated multiple paternity in these two species in an area of sympatry. We sampled 24 pregnant females (12 for each species) in Monterey Bay, California, used microsatellite analysis and assessed paternity with the COLONY software. While broods are relatively small (12 to 36 offspring), they were always sired by multiple fathers (2 to 9), with no correlation between the size of a brood and the number of fathers. The number of sires for each brood was not significantly different between the two species (approximately 3.5 sires per brood). We tested the deviation from stochasticity of fathered offspring for each father in one brood. Results showed a significant deviation for both E. jacksoni and E. lateralis. However, this deviation was not found to be significant between species. The striking similarity in the dynamics of multiple paternity in these species, when sampled in sympatry, may result from several alternative scenarios, including phylogenetic inertia, reproductive behaviour, and ecological competition.
22 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2018 | 1 |
| 2009 | 2 |
| 2005 | 1 |
| 1983 | 1 |
| 1982 | 1 |
| 1980 | 1 |