Triad hybridization via a conduit species

Introgressive hybridization can affect the evolution of populations in several important ways. It may retard or reverse divergence of species, enable the development of novel traits, enhance the potential for future evolution by elevating levels of standing variation, create new species, and alleviate inbreeding depression in small populations. Most of what is known of contemporary hybridization in nature comes from the study of pairs of species, either coexisting in the same habitat or distributed parapatrically and separated by a hybrid zone. More rarely, three species form an interbreeding complex (triad), reported in vertebrates, insects, and plants. Often, one species acts as a genetic link or conduit for the passage of genes (alleles) between two others that rarely, if ever, hybridize. Demographic and genetic consequences are unknown. Here we report results of a long-term study of interbreeding Darwin’s finches on Daphne Major island, Galápagos.Geospiza fortisacted as a conduit for the passage of genes between two others that have never been observed to interbreed on Daphne:Geospiza fuliginosa, a rare immigrant, andGeospiza scandens, a resident. Microsatellite gene flow fromG. fortisintoG. scandensincreased in frequency during 30 y of favorable ecological conditions, resulting in genetic and morphological convergence.G. fortis,G. scandens, and the derived dihybrids and trihybrids experienced approximately equal fitness. Especially relevant to young adaptive radiations, where species differ principally in ecology and behavior, these findings illustrate how new combinations of genes created by hybridization among three species can enhance the potential for evolutionary change.

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11.4 Impact of Selective Serotonin Reuptake Inhibitor (SSRI) Use on Suicidal Ideation and Behavior in Child/Adolescent Anxiety Multimodal Extended Long-Term Study

Journal of the American Academy of Child & Adolescent Psychiatry ◽

10.1016/j.jaac.2017.07.641 ◽

2017 ◽

Vol 56 (10) ◽

pp. S319

Author(s):

Dara Sakolsky

Keyword(s):

Suicidal Ideation ◽

Selective Serotonin Reuptake Inhibitor ◽

Reuptake Inhibitor ◽

Serotonin Reuptake ◽

Selective Serotonin ◽

Term Study ◽

Adolescent Anxiety ◽

Long Term Study ◽

And Behavior

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NEONATAL SEPARATION: THE MATERNAL SIDE OF INTERACTIONAL DEPRIVATION

PEDIATRICS ◽

10.1542/peds.45.2.197 ◽

1970 ◽

Vol 45 (2) ◽

pp. 197-205

Author(s):

Clicord R. Barnett ◽

P. Herbert Leiderman ◽

Rose Grobstein ◽

Marshall Klaus

Keyword(s):

Postpartum Period ◽

Infant Development ◽

Maternal Attachment ◽

Term Study ◽

Maternal Attitudes ◽

Long Term Study ◽

Pilot Model ◽

And Behavior ◽

Attitudes And Behavior

Studies of maternal behavior in nonhuman mammals have suggested that the degree of interaction permitted between mother and infant in the postpartum period will influence later maternal attachment and infant development. The hypotheses raised by these studies can be explored with human mothers and infants through manipulation of care procedures of mothers and newborns in the immediate postpartum period. A pilot study was conducted to determine the feasibility of changing premature care procedures in order to study the effects of interactional deprivation in the neonatal period on maternal attitudes and behavior. Forty-one mothers were permitted to enter the nursery and touch or handle their premature infants in incubators as early as the second day after birth. The feasibility of admitting mothers to the premature nursery without increasing the risk or occurrence of infection, or disrupting the organization of the care of the infants, was demonstrated. We are now conducting a long-term study based on this pilot model to delineate the differences in commitment, feelings of competence, and behavior in the two differentially treated groups of mothers and to relate their behavior to the motor and mental development of the infants.

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Hybridization increases population variation during adaptive radiation

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1913534116 ◽

2019 ◽

Vol 116 (46) ◽

pp. 23216-23224 ◽

Cited By ~ 11

Author(s):

Peter R. Grant ◽

B. Rosemary Grant

Keyword(s):

Introgressive Hybridization ◽

Population Variation ◽

Small Island ◽

Ecological Niches ◽

Future Evolution ◽

Adaptive Radiations ◽

Geospiza Fortis ◽

Dated Phylogeny ◽

Independent Effects ◽

Short Time

Adaptive radiations are prominent components of the world’s biodiversity. They comprise many species derived from one or a small number of ancestral species in a geologically short time that have diversified into a variety of ecological niches. Several authors have proposed that introgressive hybridization has been important in the generation of new morphologies and even new species, but how that happens throughout evolutionary history is not known. Interspecific gene exchange is expected to have greatest impact on variation if it occurs after species have diverged genetically and phenotypically but before genetic incompatibilities arise. We use a dated phylogeny to infer that populations of Darwin’s finches in the Galápagos became more variable in morphological traits through time, consistent with the hybridization hypothesis, and then declined in variation after reaching a peak. Some species vary substantially more than others. Phylogenetic inferences of hybridization are supported by field observations of contemporary hybridization. Morphological effects of hybridization have been investigated on the small island of Daphne Major by documenting changes in hybridizing populations of Geospiza fortis and Geospiza scandens over a 30-y period. G. scandens showed more evidence of admixture than G. fortis. Beaks of G. scandens became progressively blunter, and while variation in length increased, variation in depth decreased. These changes imply independent effects of introgression on 2, genetically correlated, beak dimensions. Our study shows how introgressive hybridization can alter ecologically important traits, increase morphological variation as a radiation proceeds, and enhance the potential for future evolution in changing environments.

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