scholarly journals What Do We Mean by Multicellularity? The Evolutionary Transitions Framework Provides Answers

2021 ◽  
Vol 9 ◽  
Author(s):  
Caroline J. Rose ◽  
Katrin Hammerschmidt
Keyword(s):  
Evolutionary Transitions

Evolutionary Transitions in Mode of Development

2018 ◽  
Keyword(s):  
Analytical Approach ◽  
Large Body ◽  
Functional Variation ◽  
Evolutionary Mechanisms ◽  
Evolutionary Transitions ◽  
Comparative Phylogenetics ◽  
Mode Of Development ◽  
Larval Traits ◽  
Complex Characters

In the large body of literature on ecological and evolutionary mechanisms underlying transitions between planktotrophy and lecithotrophy, the focus has typically covered long evolutionary timescales; that is, evolution of complex larval traits is generally discussed in the context of phylogenetic patterns detectable at the level of families, classes, or phyla. An analytical approach incorporating comparative phylogenetics is increasingly used to address these long-view questions. Here, we discuss what has been learned from taking a comparative phylogenetic approach and the limitations of this approach. We propose that approaches based on a closer view—that is, analyses that focus on genetic, morphological, and functional variation among individuals, populations, or closely related congeners—have greater potential to answer questions about mechanisms underlying the loss and regain of major complex characters such as feeding larvae.

scholarly journals Have Niche, Will Travel. New Means of Linking Diet and Ecomorphology Reveals Niche Conservatism in Freshwater Cottoid Fishes

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
T J Buser ◽  
D L Finnegan ◽  
A P Summers ◽  
M A Kolmann
Keyword(s):  
Niche Conservatism ◽  
Freshwater Species ◽  
Evolutionary Transitions ◽  
Adaptive Diversification ◽  
Functional Aspects ◽  
Ecological Evolution ◽  
Jaw Apparatus ◽  
Cottoid Fishes ◽  
Freshwater Habitats ◽  
Dietary Niche

Synopsis Evolutionary transitions between habitats have been catalysts for some of the most stunning examples of adaptive diversification, with novel niches and new resources providing ecological opportunity for such radiations. In aquatic animals, transitions from saltwater to freshwater habitats are rare, but occur often enough that in the Neotropics for example, marine-derived fishes contribute noticeably to regional ichthyofaunal diversity. Here, we investigate how morphology has evolved in a group of temperate fishes that contain a marine to freshwater transition: the sculpins (Percomorpha; Cottoidea). We devised a novel method for classifying dietary niche and relating functional aspects of prey to their predators. Coupled with functional measurements of the jaw apparatus in cottoids, we explored whether freshwater sculpins have fundamentally changed their niche after invading freshwater (niche lability) or if they retain a niche similar to their marine cousins (niche conservatism). Freshwater sculpins exhibit both phylogeographical and ecological signals of phylogenetic niche conservatism, meaning that regardless of habitat, sculpins fill similar niche roles in either saltwater or freshwater. Rather than competition guiding niche conservatism in freshwater cottoids, we argue that strong intrinsic constraints on morphological and ecological evolution are at play, contra to other studies of diversification in marine-derived freshwater fishes. However, several intertidal and subtidal sculpins as well as several pelagic freshwater species from Lake Baikal show remarkable departures from the typical sculpin bauplan. Our method of prey categorization provides an explicit, quantitative means of classifying dietary niche for macroevolutionary studies, rather than relying on somewhat arbitrary means used in previous literature.

scholarly journals Understanding plant reproductive diversity

2010 ◽  
Vol 365 (1537) ◽  
pp. 99-109 ◽  
Author(s):  
Spencer C. H. Barrett
Keyword(s):  
Reproductive Biology ◽  
Flowering Plants ◽  
Future Research ◽  
Wind Pollination ◽  
Evolutionary Patterns ◽  
Evolutionary Transitions ◽  
Floral Diversity ◽  
Self Fertilization ◽  
Personal Reflections ◽  
Animal Pollination

Flowering plants display spectacular floral diversity and a bewildering array of reproductive adaptations that promote mating, particularly outbreeding. A striking feature of this diversity is that related species often differ in pollination and mating systems, and intraspecific variation in sexual traits is not unusual, especially among herbaceous plants. This variation provides opportunities for evolutionary biologists to link micro-evolutionary processes to the macro-evolutionary patterns that are evident within lineages. Here, I provide some personal reflections on recent progress in our understanding of the ecology and evolution of plant reproductive diversity. I begin with a brief historical sketch of the major developments in this field and then focus on three of the most significant evolutionary transitions in the reproductive biology of flowering plants: the pathway from outcrossing to predominant self-fertilization, the origin of separate sexes (females and males) from hermaphroditism and the shift from animal pollination to wind pollination. For each evolutionary transition, I consider what we have discovered and some of the problems that still remain unsolved. I conclude by discussing how new approaches might influence future research in plant reproductive biology.

scholarly journals Are evolutionary transitions in sexual size dimorphism related to sex determination in reptiles?

2021 ◽  
Vol 34 (4) ◽  
pp. 594-603
Author(s):  
Gergely Katona ◽  
Balázs Vági ◽  
Zsolt Végvári ◽  
András Liker ◽  
Robert P. Freckleton ◽  
...  
Keyword(s):  
Sex Determination ◽  
Sexual Size Dimorphism ◽  
Evolutionary Transitions ◽  
Size Dimorphism

scholarly journals Evolutionary transitions between mechanisms of sex determination in vertebrates

2011 ◽  
Vol 7 (3) ◽  
pp. 443-448 ◽  
Author(s):  
Alexander E. Quinn ◽  
Stephen D. Sarre ◽  
Tariq Ezaz ◽  
Jennifer A. Marshall Graves ◽  
Arthur Georges
Keyword(s):  
Sex Determination ◽  
Chromosome Pair ◽  
Sex Chromosome ◽  
Molecular Pathways ◽  
Genetic Contribution ◽  
Temperature Dependent ◽  
Trait Evolution ◽  
Evolutionary Transitions ◽  
Dichotomous Outcome ◽  
Threshold Trait

Sex in many organisms is a dichotomous phenotype—individuals are either male or female. The molecular pathways underlying sex determination are governed by the genetic contribution of parents to the zygote, the environment in which the zygote develops or interaction of the two, depending on the species. Systems in which multiple interacting influences or a continuously varying influence (such as temperature) determines a dichotomous outcome have at least one threshold. We show that when sex is viewed as a threshold trait, evolution in that threshold can permit novel transitions between genotypic and temperature-dependent sex determination (TSD) and remarkably, between male (XX/XY) and female (ZZ/ZW) heterogamety. Transitions are possible without substantive genotypic innovation of novel sex-determining mutations or transpositions, so that the master sex gene and sex chromosome pair can be retained in ZW–XY transitions. We also show that evolution in the threshold can explain all observed patterns in vertebrate TSD, when coupled with evolution in embryonic survivorship limits.

scholarly journals Trends in flower symmetry evolution revealed through phylogenetic and developmental genetic advances

2014 ◽  
Vol 369 (1648) ◽  
pp. 20130348 ◽  
Author(s):  
Lena C. Hileman
Keyword(s):  
Bilateral Symmetry ◽  
Radial Symmetry ◽  
Plant Evolution ◽  
Flowering Plant ◽  
Developmental Studies ◽  
Developmental Genetic ◽  
Evolutionary Transitions ◽  
Flower Symmetry ◽  
Molecular Phylogenetic ◽  
Developmental Programme

A striking aspect of flowering plant (angiosperm) diversity is variation in flower symmetry. From an ancestral form of radial symmetry (polysymmetry, actinomorphy), multiple evolutionary transitions have contributed to instances of non-radial forms, including bilateral symmetry (monosymmetry, zygomorphy) and asymmetry. Advances in flowering plant molecular phylogenetic research and studies of character evolution as well as detailed flower developmental genetic studies in a few model species (e.g. Antirrhinum majus , snapdragon) have provided a foundation for deep insights into flower symmetry evolution. From phylogenetic studies, we have a better understanding of where during flowering plant diversification transitions from radial to bilateral flower symmetry (and back to radial symmetry) have occurred. From developmental studies, we know that a genetic programme largely dependent on the functional action of the CYCLOIDEA gene is necessary for differentiation along the snapdragon dorsoventral flower axis. Bringing these two lines of inquiry together has provided surprising insights into both the parallel recruitment of a CYC -dependent developmental programme during independent transitions to bilateral flower symmetry, and the modifications to this programme in transitions back to radial flower symmetry, during flowering plant evolution.

Molluscan biostratigraphy of the lower River Bend Formation at the Martin Marietta Quarry, New Bern, North Carolina

1991 ◽  
Vol 65 (1) ◽  
pp. 80-118 ◽  
Author(s):  
Thomas J. Rossbach ◽  
Joseph G. Carter
Keyword(s):  
North Carolina ◽  
Coastal Plain ◽  
Warm Water ◽  
Gulf Coastal Plain ◽  
Generic Level ◽  
Evolutionary Transitions ◽  
Molluscan Fauna ◽  
Molluscan Diversity ◽  
Molluscan Species ◽  
River Bend

The lower River Bend Formation at the Martin Marietta New Bern quarry in Craven County, North Carolina, contains a diverse and abundant moldic molluscan fauna. This fauna, reconstructed by latex casts, suggests a Vicksburgian or a post-Vicksburgian, pre-Chickasawhayan age for the New Bern exposure. Forty-one molluscan species and subspecies are presently identified from the lower River Bend Formation, 11 of which are new: Turritella caelatura alani, Turritella neusensis, Galeodaria britti, Phalium newbernensis, Cymatium planinodum, Oocorys vadosus, Ecphora wheeleri, Lyria concinna, Scaphella saintjeani, Turricula (Orthosurcula) aequa, and Lucina (Stewartia) micraulax. This fauna is virtually identical at the generic level and similar at the species level to the Vicksburgian faunas of the Gulf Coastal Plain. About 37 percent of the New Bern species also occur in the Vicksburgian of Mississippi, although many of these species reach considerably larger sizes at New Bern. Apparent evolutionary transitions between previously known Vicksburgian and Chickasawhayan mollusks suggest a time of deposition intermediate between these two Oligocene stages.Moderately high molluscan diversity, the abundance of characteristically warm-water genera, and associated carbonate-rich sediments suggest that the lower River Bend Formation represents a subtropical, open-marine, predominantly carbonate environment immediately seaward of a nearshore lagoonal or barrier island complex.The lower River Bend Formation at New Bern differs faunally, climatically, and sedimentologically from the upper River Bend Formation in quarry exposures near Belgrade, North Carolina. The upper River Bend Formation contains a lower diversity molluscan fauna with marked dominance diversity and few warm-water taxa. It represents a slightly cooler nearshore, open-marine environment in a transitional siliciclastic-carbonate sedimentary regime. The considerable taxonomic and sedimentologic differences between the lower and upper parts of the River Bend Formation corroborate microfossil evidence suggesting that they represent temporally distinct depositional cycles.

scholarly journals The Vav GEF Family: An Evolutionary and Functional Perspective

Cells ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 465 ◽  
Author(s):  
Sonia Rodríguez-Fdez ◽  
Xosé R. Bustelo
Keyword(s):  
Tyrosine Kinases ◽  
Rho Gtpases ◽  
Nucleotide Exchange ◽  
Structural Domains ◽  
Evolutionary Transitions ◽  
Functional Perspective ◽  
Nucleotide Exchange Factors ◽  
The Family ◽  
Unicellular Organisms ◽  
Phylogenetic Perspective

Vav proteins play roles as guanosine nucleotide exchange factors for Rho GTPases and signaling adaptors downstream of protein tyrosine kinases. The recent sequencing of the genomes of many species has revealed that this protein family originated in choanozoans, a group of unicellular organisms from which animal metazoans are believed to have originated from. Since then, the Vav family underwent expansions and reductions in its members during the evolutionary transitions that originated the agnates, chondrichthyes, some teleost fish, and some neoaves. Exotic members of the family harboring atypical structural domains can be also found in some invertebrate species. In this review, we will provide a phylogenetic perspective of the evolution of the Vav family. We will also pay attention to the structure, signaling properties, regulatory layers, and functions of Vav proteins in both invertebrate and vertebrate species.

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