Paleozoic origins of cheilostome bryozoans and their parental care inferred by a new genome-skimmed phylogeny

Abstract

Phylogenetic relationships and the timing of evolutionary events are essential for understanding evolution on longer time scales. Cheilostome bryozoans are a group of ubiquitous, species-rich, marine colonial organisms with an excellent fossil record but lack phylogenetic relationships inferred from molecular data. We present genome-skimmed data for 395 cheilostomes and combine these with 315 published sequences to infer relationships and the timing of key events among c. 500 cheilostome species. We find that named cheilostome genera and species are phylogenetically coherent, rendering fossil or contemporary specimens readily delimited using only skeletal morphology. Our phylogeny shows that parental care in the form of brooding evolved several times independently but was never lost in cheilostomes. Our fossil calibration, robust to varied assumptions, indicates that the cheilostome lineage and parental care therein could have Paleozoic origins, much older than the first known fossil record of cheilostomes in the Late Jurassic.

Phylogenomics reveals deep relationships and diversification within phylactolaemate bryozoans

“…The monophyly of these three classes has been supported by the molecular studies of Fuchs et al [7], Waeschenbach et al [8] and Orr et al [9]. Phylactolaemata is recognized to be the earliest extant branch and as the sister clade of the remaining bryozoan clades [7][8][9][10]. Stenolaemata and Gymnolaemata were recently united by Schwaha et al [11] in one clade called Myolaemata based on existing molecular studies and soft tissue morphology.…”

Temperature as a likely driver shaping global patterns in mineralogical composition in bryozoans: Implications for marine calcifiers under Global Change

“…They are dominant members of many benthic communities, including the Antarctic region (Barnes & Kuklinski, 2010; Figuerola et al, 2012). Many species are major carbonate sediment producers, thus being well represented in the fossil record (Taylor, 2020) and good model systems for understanding ecological and evolutionary processes (Orr et al, 2022). The calcareous skeletons of bryozoans can be entirely calcitic, aragonitic or bimineralic, and incorporate varying amounts of Mg in their calcite, ranging from low Mg-calcite (LMC; <4 wt% MgCO 3 ), through intermediate Mg-calcite (IMC; 4−8%), to high Mg-calcite (HMC; >8%) following the categories proposed by Rucker and Carver (1969) (see Taylor et al, 2015).…”

“…Many species are major carbonate sediment producers, thus being well represented in the fossil record (Taylor, 2020) and good model systems for understanding ecological and evolutionary processes (Orr et al, 2022). following the categories proposed by Rucker and Carver (1969) (see Taylor et al, 2015).…”

Changing allometric relationships among fossil and Recent populations in two colonial species

“…A vast number of these organisms could easily be collected from fossil outcrops, which can then be subjected to automated phenotyping (Lürig et al 2021) allowing much speedier data collection. A total-evidence cheilostome phylogeny is estimable given the ground work already done (Orr et al 2021(Orr et al , 2022, and quantitative genetics experiments are also viable as some of these species are extant. Using our model system, we now know that empirical allometric relationships can evolve on shorter timescales than seen before in natural systems (e.g., Voje and Hansen 2013), and that some traits (measured on the same genetic individual) are more subject to constraints than others.…”