What Molecular Phylogenies Tell Us about the Evolution of Larval Forms

Strathmann, Richard R.; Eernisse, Douglas J.

doi:10.1093/icb/34.4.502

Cited by 83 publications

(71 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Because very large eggs in the arcids and other bivalves are associated with nonplanktotrophic development (Strathmann 1987;Moran 2004), this scenario implies that planktotrophy has evolved from nonplanktotrophy numerous times in the arcid tree. This evolutionary scenario is unlikely; planktotrophy is considered to be the ancestral state in the majority of higher invertebrate taxa, and the switch from nonplanktotrophy to planktotrophy is thought to be rare in most marine invertebrate groups (Strathmann 1985;Strathmann and Eernisse 1994;Havenhand 1995;Hart et al 1997;Cunningham 1999;Duda and Palumbi 1999;Jeffery and Emlet 2003;but see Reid 1989;Rouse 2000;Kupriyanova 2003).…”

Section: Phylogenetic Ancestral Character State Reconstructionsmentioning

confidence: 99%

Egg Size Evolution in Tropical American Arcid Bivalves: The Comparative Method and the Fossil Record

Moran¹

2004

Evolution

View full text Add to dashboard Cite

Abstract.•Marine organisms exhibit a wide range of egg sizes, even among closely related taxa, and egg size is widely considered to be one of the most important components of the life histories of marine species. The nature of the trade-off between egg size and number and the consequences of variation in egg size for offspring growth and survivorship have been extensively modeled. Yet, there is little empirical evidence that supports the relative importance of particular environmental parameters in engendering the tremendous variation in egg size seen in marine organisms. This study compares egg sizes between six geminate species pairs of bivalves in the family Arcidae to determine whether egg size differs in predictable directions between geminate species in the two oceans separated by the Central American isthmus, and whether the direction and timing of egg size evolution among geminates in this family is correlated with both modern and paleoceanographic patterns of oceanic productivity. In all modern members of six geminate pairs, egg size was larger in the species in the western Atlantic than in its sister species the eastern Pacific. This pattern supports the hypothesis that optimal egg size differs in the two oceans due to the low productivity and poor larval feeding environment in the western Atlantic relative to the eastern Pacific. The fossil record of one geminate pair shows that egg size has remained consistently large in the western Atlantic from the Miocene to the Recent, while egg size in the eastern Pacific has decreased to the current small size in less than 2 million years; this suggests that modern-day differences between egg sizes in the western Atlantic and eastern Pacific are due to either an increase in productivity in the eastern Pacific and subsequent selection for smaller eggs in that ocean, or differential patterns of extinction that occurred well after the rise of the isthmus. These results agree with ancestral character state reconstruction using linear parsimony, but differ from squared-change parsimony reconstructions. Egg size is widely considered to be one of the most important components of the life histories of marine organisms

show abstract

Section: Phylogenetic Ancestral Character State Reconstructionsmentioning

confidence: 99%

Egg Size Evolution in Tropical American Arcid Bivalves: The Comparative Method and the Fossil Record

Moran¹

2004

Evolution

View full text Add to dashboard Cite

show abstract

“…One main question regarding larval form is whether similarities in larval morphology are phylogenetically linked or if the body plans of larvae are free to evolve, arriving at similar morphologies based on convergent selective pressures (McEdward and Janies, 1993;Strathmann and Eernisse, 1994;Wray, 2002;Santagata, 2004;Raff and Byrne, 2006). Several investigations have concluded that the transition from a feeding to a nonfeeding larva (or vice versa) is a common evolutionary switch among marine invertebrates having no significant phylogenetic signal (Hart et al, 1997;Duda and Palumbi, 1999;Nü tzel et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

The morphology and evolutionary significance of the ciliary fields and musculature among marine bryozoan larvae

Santagata

2007

Journal of Morphology

View full text Add to dashboard Cite

Despite the embryological and anatomical disparities present among lophotrochozoan phyla, there are morphological similarities in the cellular arrangements of ciliated cells used for propulsion among the nonfeeding larval forms of kamptozoans, nemerteans, annelids, mollusks, and bryozoans. Evaluating whether these similarities are the result of convergent selective pressures or a shared (deep) evolutionary history is hindered by the paucity of detailed cellular information from multiple systematic groups from lesser-known, and perhaps, basal evolutionary phyla such as the Bryozoa. Here, I compare the ciliary fields and musculature among the major morphological grades of marine bryozoan larvae using light microscopy, SEM, and confocal imaging techniques. Sampling effort focused on six species from systematic groups with few published accounts, but an additional four well-known species were also reevaluated. Review of the main larval types among species of bryozoans and these new data show that, within select systematic groups of marine bryozoans, there is some conservation of the cellular arrangement of ciliary fields and larval musculature. However, there is much more morphological diversity in these structures than previously documented, especially among nonfeeding ctenostome larval types. This structural and functional diversification reflects species differences in the orientation of the apical disc during swimming and crawling behaviors, modification of the presumptive juvenile tissues, elongation of larval forms in the aboral-oral axis, maximizing the surface area of cell types with propulsive cilia, and the simplification of ciliary fields and musculature within particular lineages due to evolutionary loss. Considering the embryological origins and functional plasticity of ciliated cells within bryozoan larvae, it is probable that the morphological similarities shared between the coronal cells of bryozoan larvae and the prototrochal cells of trochozoans are the result of convergent functional solutions to swimming in the plankton. However, this does not rule out cell specification pathways shared by more closely related spiralian phyla. Overall, among the morphological grades of larval bryozoans, the structural variation and arrangement of the main cell groups responsible for ciliary propulsion have been evolutionarily decoupled from the more divergent modifications of larval musculature. The structure of larval ciliary fields reflects the functional demands of swimming and substrate exploration behaviors before metamorphosis, but this is in contrast to the morphology of larval musculature and presumptive juvenile tissues that are linked to macroevolutionary differences in morphogenetic movements during metamorphosis.

show abstract

“…Rouse & Fitzhugh 1994, Hadfield et al 1997, Ponder & Lindberg 1997reviewed by Nielsen 1998), it is generally believed that free-living larvae of some sort are primitive in marine invertebrate life histories and that the loss of larval stages is a derived condition (e.g. Berrill 1931, Jagersten 1972, Hoagland 1986, Jackson 1986, Strathmann 1986, Emlet et al 1987, Raff 1987, Reid 1989, Giangrande et al 1994, Page 1994, Rawlings 1994, Mooi & David 1993, Rieger 1994, Strathmann & Eernisse 1994, Havenhand 1995, Wray 1995, Bhaud & DuchBne 1996, Byrne & Cerra 1996, Hart et al 1997, Ponder & Lindberg 1997, Nielsen 1998). This assumption is supported by logical argument and intuition, and by some cladistic analyses (e.g.…”

Section: Introductionmentioning

confidence: 99%

On the advantages and disadvantages of larval stages in benthic marine invertebrate life cycles

Pechenik¹

1999

Mar. Ecol. Prog. Ser.

589

424

View full text Add to dashboard Cite

many benthic marine invertebrates develop by means of free-livlng, dispersive larval stages. The presumed advantages of such larvae include the avoidance of competition for resources with adults, temporary reduct~on of benthic mortality while in the plankton, decreased likelihood of inbreeding in the next generation, and increased ability to withstand local extinction However, the direct~on of evolutionary change appears generally b~a s e d toward the loss of larvae in many clades, implying that larvae are somehow disadvantageous. Poss~ble disadvantages include dispersal away from favorable habitat, mismatches between larval and luvenile physiological tolerances, greater susceptib~lity to env~ronmental stresses, greater susceptibihty to predation. and vanous costs that may be associated with n~etanlorphosing in response to specific chemical cues and postponing n~etamorphosis in the absence of those cues. Understanding the forces responsible for the present distribution of larval and non-larval (aplanktonlc) development among benthic marine invertebrates, and the potential influence of human activities on the direct~on of future evolutionary change in 1-eproductlve patterns, will require a better understanding of the following issues. the role of macro-evolutionary forces in selecting for or against dispersive larvae, the relative tolerances of encapsulated embryos and free-living larvae to salinity, pollutant, and other environmental stresses; the degree to which egg masses, e g g capsules, and brood chambers protect developing embryos from environmental stresses; the relative magmtude of predation by planktonic and benthic predators on both larvae and early juveniles; the way In which larval and juvenile size affect vulnerability to predators; the extent to w h~c h encapsulation and brooding protect against predators; the amount of genetic change associated with loss of larvae from invertebrate life cycles and the time required to accomplish that change; and the degree to which continued input of larvae from other populations deters selection against dispersive larvae The prominence of larval development in modern life cycles may reflect difficulties In loslng larvae from llfe cycles more than selection for their retention.

show abstract

What Molecular Phylogenies Tell Us about the Evolution of Larval Forms

Cited by 83 publications

References 38 publications

Egg Size Evolution in Tropical American Arcid Bivalves: The Comparative Method and the Fossil Record

Egg Size Evolution in Tropical American Arcid Bivalves: The Comparative Method and the Fossil Record

The morphology and evolutionary significance of the ciliary fields and musculature among marine bryozoan larvae

On the advantages and disadvantages of larval stages in benthic marine invertebrate life cycles

Contact Info

Product

Resources

About