Concepts

25 concept cards. Each card defines one piece of jargon used across the lab’s topic pages — meiotic sex chromosome inactivation, pseudoautosomal region, sexually antagonistic selection, and so on. Every card links to its primary source finding and to the topics that use it.

On any topic page, the first mention of a term below is auto-wrapped in a dotted underline; hover reveals the definition without leaving the page. Click the link to read the full card.

Introductory

Autosome — An autosome is any chromosome that is present in the same number and form in both sexes — every chromosome except the sex chromosomes.
Chromosome Fusion — A chromosome fusion is a structural rearrangement that joins two previously separate chromosomes into one, reducing the total chromosome number by one and…
Heterogamety — A species is heterogametic in one sex when that sex produces two different kinds of gametes, one carrying each of two distinct sex chromosomes (e.g.,…
Sex Determination — Sex determination is the developmental process by which an organism’s sex is established — either through genetic mechanisms (GSD), environmental cues…

Intermediate

Ancestral State Reconstruction — Ancestral state reconstruction (ASR) is a phylogenetic method for inferring the most probable trait values of ancestral species given a tree topology,…
Aneuploidy — Aneuploidy is the condition of having an incorrect number of chromosomes in a cell, typically caused by chromosomes failing to separate properly during…
Dysploidy — Dysploidy is a change in chromosome number by one or a small number of whole chromosomes through fusion (reducing count) or fission (increasing count) — as…
Effective Population Size — Effective population size (Ne) is the size of an idealized population that would experience the same rate of genetic drift as the actual population,…
Haldane’s Rule — Haldane’s rule states that when only one sex is sterile or inviable in interspecific hybrids, it is disproportionately the heterogametic sex (XY males or ZW…
Holocentric Chromosome — A holocentric chromosome has centromere activity distributed along its entire length rather than restricted to a single point, so spindle fibers can attach…
Hybrid Sterility — Hybrid sterility is the failure of hybrids between two species or populations to reproduce, caused by incompatible gene combinations (Dobzhansky-Muller…
Meiotic Sex Chromosome Inactivation — Meiotic sex chromosome inactivation (MSCI) is the transcriptional silencing of the X and Y chromosomes during male meiosis, which creates strong selection…
Mk Model — The Mk model is a continuous-time Markov chain for discrete trait evolution on a phylogeny, where each trait state can transition to any other at a rate…
Neo-Sex Chromosome — A neo-sex chromosome is a newly derived sex chromosome formed when an autosome fuses with, or is recruited as a replacement for, an existing sex chromosome…
Polyploidy — Polyploidy is the state of having more than two complete sets of chromosomes in a cell — typically arising from whole-genome duplication or hybridization…
Pseudoautosomal Region — The pseudoautosomal region (PAR) is the segment of the sex chromosomes where X and Y (or Z and W) still recombine with each other — behaving like autosomes…
Recombination Suppression — Recombination suppression in sex chromosomes is the evolutionary reduction or elimination of crossovers between X and Y (or Z and W) in the sex-limited…
Robertsonian Translocation — A Robertsonian translocation is a specific type of chromosome fusion where two acrocentric (short-armed) chromosomes join at their centromeres, producing a…
SA Fusion — An SA fusion is a chromosomal fusion between a sex chromosome and an autosome that is favored by selection because it links a sexually antagonistic allele…
Sexual Antagonism — Sexual antagonism occurs when an allele at a locus increases the fitness of one sex while decreasing the fitness of the other — creating an evolutionary…

Advanced

Achiasmy — Achiasmy is the complete absence of crossovers (chiasmata) during meiosis in one sex, eliminating the obligate crossover that normally tethers homologous…
BiSSE — BiSSE (Binary State Speciation and Extinction) is a phylogenetic model that jointly estimates speciation and extinction rates for each state of a binary…
Demiploidy — Demiploidy (often called haplodiploidy) is a reproductive system in which females develop from fertilized diploid eggs while males develop from unfertilized…
Retrogene — A retrogene is an mRNA-derived copy of a gene that has been reverse-transcribed and reinserted into the genome at a new location — typically losing introns…
SIMMAP — SIMMAP (Stochastic Mapping) is a Bayesian method that samples complete histories of character-state transitions mapped continuously onto each branch of a…