Brood chambers (ovicells) of cheilostome bryozoans (bryozoa: Gymnolaemata): structure, research history, and modern problematics

Ostrovskii, A. N.

doi:10.1007/s11179-005-0025-6

Cited by 7 publications

(3 citation statements)

References 42 publications

(91 reference statements)

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“…Compared with all aquatic invertebrates, Bryozoa have the widest within‐phylum taxonomic distribution of placental analogues, unusually diverse incubational structures, and numerous instances of incipient matrotrophy (Ostrovsky et al ., ; Ostrovsky, 2013 a , b , see also Ostrovsky & Schäfer, ; Ostrovskii, ; Ostrovsky, ; Ostrovsky, Vávra & Porter, ). As a reproductive strategy, yolky eggs combined with low levels of parental provisioning is well known among vertebrates (Blackburn, ; Pollux et al ., , see also Section III), and considered by some workers as an initial step in the evolution of advanced substantial matrotrophy (Stewart & Thompson, , ).…”

Section: Resultsmentioning

confidence: 91%

Matrotrophy and placentation in invertebrates: a new paradigm

et al. 2015

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Matrotrophy, the continuous extra‐vitelline supply of nutrients from the parent to the progeny during gestation, is one of the masterpieces of nature, contributing to offspring fitness and often correlated with evolutionary diversification. The most elaborate form of matrotrophy—placentotrophy—is well known for its broad occurrence among vertebrates, but the comparative distribution and structural diversity of matrotrophic expression among invertebrates is wanting. In the first comprehensive analysis of matrotrophy across the animal kingdom, we report that regardless of the degree of expression, it is established or inferred in at least 21 of 34 animal phyla, significantly exceeding previous accounts and changing the old paradigm that these phenomena are infrequent among invertebrates. In 10 phyla, matrotrophy is represented by only one or a few species, whereas in 11 it is either not uncommon or widespread and even pervasive. Among invertebrate phyla, Platyhelminthes, Arthropoda and Bryozoa dominate, with 162, 83 and 53 partly or wholly matrotrophic families, respectively. In comparison, Chordata has more than 220 families that include or consist entirely of matrotrophic species. We analysed the distribution of reproductive patterns among and within invertebrate phyla using recently published molecular phylogenies: matrotrophy has seemingly evolved at least 140 times in all major superclades: Parazoa and Eumetazoa, Radiata and Bilateria, Protostomia and Deuterostomia, Lophotrochozoa and Ecdysozoa. In Cycliophora and some Digenea, it may have evolved twice in the same life cycle. The provisioning of developing young is associated with almost all known types of incubation chambers, with matrotrophic viviparity more widespread (20 phyla) than brooding (10 phyla). In nine phyla, both matrotrophic incubation types are present. Matrotrophy is expressed in five nutritive modes, of which histotrophy and placentotrophy are most prevalent. Oophagy, embryophagy and histophagy are rarer, plausibly evolving through heterochronous development of the embryonic mouthparts and digestive system. During gestation, matrotrophic modes can shift, intergrade, and be performed simultaneously. Invertebrate matrotrophic adaptations are less complex structurally than in chordates, but they are more diverse, being formed either by a parent, embryo, or both. In a broad and still preliminary sense, there are indications of trends or grades of evolutionarily increasing complexity of nutritive structures: formation of (i) local zones of enhanced nutritional transport (placental analogues), including specialized parent–offspring cell complexes and various appendages increasing the entire secreting and absorbing surfaces as well as the contact surface between embryo and parent, (ii) compartmentalization of the common incubatory space into more compact and ‘isolated’ chambers with presumably more effective nutritional relationships, and (iii) internal secretory (‘milk’) glands. Some placental analogues in onychophorans and arthropods mimi...

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Section: Resultsmentioning

confidence: 91%

Matrotrophy and placentation in invertebrates: a new paradigm

et al. 2015

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“…Subsidiary features of the frontal shield, primary and peristomial orifices and avicularia allow discrimination among the many species in these two genera, as is the case in many other cheilostome genera and families (e.g. Gordon 1993;Ostrovsky 2004;Vieira et. al.…”

Section: Discussionmentioning

confidence: 99%

Taxonomic review of the family Colatooeciidae Winston, 2005 (Bryozoa, heilostomata), with description of seven new species

Almeida¹,

Souza²,

Menegola³

et al. 2014

Zootaxa

978

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“…Many cheilostome bryozoans today have evolved division of labor, where their 'zooids', or colony members, perform specialized tasks within the colony and express different morphologies, termed polymorphism (3,(14)(15)(16)(17). The most common polymorphs include: autozooids that feed and produce gametes, ovicells that brood embryos (18), and avicularia that perform varied tasks from defense to hygiene ( [13], Fig. 1).…”

Section: Testing Evolutionary Models For the Division Of Labor In Bry...mentioning

confidence: 99%

Origin of division of labor is decoupled from polymorphism in colonial animals

Leventhal,

Edie,

Morrison

et al. 2024

Preprint

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Division of labor, the specialization of sometimes phenotypically divergent cell types or group members, is often associated with ecological success in eukaryotic colonial organisms. Despite its many independent evolutionary origins, how division of labor originates remains unclear. Conventional hypotheses tend towards an “economic” model, so that biological division of labor may reflect a partitioning of pre-existing tasks and morphologies into specialized colony members. Here, we present an alternative model of the origin of division of labor, which can explain the evolution of new functions within a colony. We show that in colonies of the Cretaceous aged (103-96 Ma) fossil bryozoan of the genusWilbertopora, the first cheilostome bryozoan to evolve polymorphism, new member morphologies were not a simple partitioning of pre-existing morphologies, but instead expanded into novel morphospace as they lost functions, specifically feeding. This expansion into new morphologies occurred primarily during two pulses of heightened morphological disparity, suggesting that the evolution of polymorphism corresponded to relaxed constraints on morphology and perhaps to the exploration of novel functions. Using a simple model of physiological connections, we show that regardless of the functionality of these new colony members, all non-feeding members could have been supported by neighboring feeding members. This suggests that the geometric constraints and physiological connectedness could be prerequisites for evolving both polymorphism and division of labor in modular organisms, and that a classic partitioning model of specialization cannot be broadly applied to biological systems.One Sentence summaryIn cheilostome bryozoans, polymorphism evolved through the loss of preexisting functions, rather than the gain of new functions, suggesting that polymorphism can evolve through drift rather than division of labor.

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Brood chambers (ovicells) of cheilostome bryozoans (bryozoa: Gymnolaemata): structure, research history, and modern problematics

Cited by 7 publications

References 42 publications

Matrotrophy and placentation in invertebrates: a new paradigm

Matrotrophy and placentation in invertebrates: a new paradigm

Taxonomic review of the family Colatooeciidae Winston, 2005 (Bryozoa, heilostomata), with description of seven new species

Origin of division of labor is decoupled from polymorphism in colonial animals

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