Botany

Systematics

The study of biological diversity and its evolutionary history.

Phylogeny

The hypothetical evolutionary history/relationship among organisms.

Taxonomy

The science of classification and naming organisms.

Systematics vs taxonomy

Taxonomy focuses on naming/classifying; systematics also emphasizes evolutionary relationships.

Importance of systematics

It lets us describe, document, name, compare, conserve, and communicate about biodiversity.

Type specimen

A reference specimen that anchors the scientific name of a species.

Holotype

The single main specimen originally chosen to define a species.

Isotype

A duplicate of the holotype collection, common in botany.

Lectotype

A specimen selected later to serve as the type when no holotype was chosen or the holotype is lost.

Paratype

An additional specimen cited in the original description that supports the species description but is not the main type.

Taxonomic rank order

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

Bryophytes

Nonvascular land plants such as mosses, liverworts, and hornworts; gametophyte-dominant.

Pteridophytes

Seedless vascular plants such as ferns and horsetails; sporophyte-dominant but reproduce by spores.

Gymnosperms

Seed plants with naked seeds not enclosed in fruit; examples include conifers, cycads, ginkgo, and gnetophytes.

Angiosperms

Flowering plants with seeds enclosed in an ovary that becomes fruit.

Monocots

Angiosperms with one cotyledon, parallel veins, scattered vascular bundles, flower parts often in 3s, and monosulcate pollen.

Sporophyte

The diploid 2n generation that produces spores by meiosis.

Gametophyte

The haploid n generation that produces gametes by mitosis.

Apocarpy

Distinct, separate carpels.

Syncarpy

Fused carpels.

Homoplasy

Similar-looking traits that evolved independently and do not indicate close relationship.

Biological species concept

Species are groups of interbreeding populations reproductively isolated from other groups.

Morphological species concept

Species are separated by detectable physical/morphological discontinuities.

Speciation

The evolutionary process by which one species splits into two or more species.

Allopatric speciation

Speciation through geographic separation.

Sympatric speciation

Speciation in the same geographic area, often through polyploidy or ecological shifts.

Polyploidy

Condition where an organism has more than two complete sets of chromosomes.

Outbreeding

Sexual reproduction between different individuals; also called outcrossing, allogamy, or xenogamy.

Inbreeding depression

Reduced fitness caused by increased expression of harmful recessive alleles.

Coevolution

Reciprocal evolutionary change between interacting species.

Mutualism

Interaction where both species benefit.

Antagonism

Interaction where one species benefits while the other is harmed.

Frugivory

Fruit eating; animals get food and may disperse seeds.

Isolation mechanism

Factors that limit gene flow between populations.

Mechanisms of isolation

Geographic, ecological, premating, and postmating mechanisms that prevent interbreeding.

Nectar

Sugary energy reward for pollinators.

Fertilization

Fusion of sperm and egg to form an embryo/new sporophyte.

Hercogamy

Spatial separation of anthers and stigmas.

Dichogamy

Different timing of male and female floral function.

Asexual reproduction

Reproduction without meiosis or fertilization.