Fungi, Reproduction, and Speciation: Key Concepts in Biology Save Groups

Fungi

Eukaryotic; they are multicellular eukaryotes (except for unicellular yeasts).

Primary structural component of the fungal cell wall

Chitin.

Mode of nutrition in fungi

They secrete exoenzymes to break down organic matter externally and then absorb the nutrients. This is called absorptive nutrition.

Primary ecological role of most fungi

They are saprophytes or decomposers, breaking down dead organic material.

Main reproductive cells of fungi

Spores (both sexual and asexual).

Clade shared by fungi and animals

Opisthokonta.

Entire, interwoven body of a fungus

Mycelium.

Long, tubular filaments that make up the mycelium

Hyphae.

Fusion of cytoplasm from two different fungal hyphae

Plasmogamy.

Ploidy and term for a hypha that contains two separate, haploid nuclei (n+n)

It is dikaryotic or heterokaryotic.

Fusion of nuclei in the fungal life cycle

Karyogamy.

What karyogamy produces

A diploid (2n) zygote.

Where karyogamy typically occurs in terrestrial fungi

Within a specialized structure like a fruiting body, ascocarp, basidiocarp, or zygosporangium.

Yeasts

Unicellular fungi.

Molds

Rapidly growing, asexually reproducing fungi.

Mycorrhiza

A symbiotic association between a fungus and a plant root, where the fungus receives carbohydrates from the plant and the plant gains improved uptake of water and nutrients like phosphorus and nitrogen

What the fungus provides to the plant in mycorrhizal symbiosis

Water and minerals.

What the plant provides to the fungus in mycorrhizal symbiosis

Carbohydrates (sugars).

Color of spores produced by rusts on plant leaves

Red.

Common fungal skin infections in humans

Ringworm and Athlete's foot.

Serious fungal infection in California caused by a soil fungus

San Joaquin Valley Fever.

Fungal partner in a lichen

The mycobiont.

Algal or cyanobacterial partner in a lichen

The phycobiont.

Small, asexual reproductive structures produced by lichens

Soredia.

Ecological significance of lichens in terms of colonizing new land

They were likely among the first organisms to colonize land, possibly before plants.

Biological Species Concept

A group of populations whose members have the potential to interbreed in nature and produce fertile offspring.

Main problem with the Biological Species Concept regarding hybrids

It struggles to classify hybrids, which can sometimes be fertile.

Main problem with the Biological Species Concept regarding extinct species

It is impractical and cannot be applied to fossils or extinct species.

What must develop between populations for a new species to form

A reproductive barrier (isolation) to gene flow.

Key factor that initiates allopatric speciation

Geographic isolation (a physical barrier that separates populations).

How the Grand Canyon serves as an example of allopatric speciation

It acted as a geographic barrier, separating squirrel populations (e.g., antelope squirrels) and blocking gene flow.

How the Isthmus of Panama led to allopatric speciation

The land bridge formed, separating marine populations (like snapping shrimp) into Atlantic and Pacific groups, blocking gene flow.

Where sympatric speciation occurs relative to the parent population

Within the same geographic area (within the home range of the ancestral species).

Three common mechanisms that can lead to sympatric speciation

Genetic (like polyploidy), Behavioral, or Temporal isolation.

Type of reproductive barrier in the example of the white-crowned sparrows

A pre-zygotic barrier.

Why horses and donkeys are considered separate species despite producing offspring (mules)

Due to a post-zygotic barrier; the hybrids (mules) are sterile (reduced hybrid fertility).

Allopatric speciation

Speciation that occurs when a geographic barrier separates populations, blocking gene flow.

Sympatric speciation

Speciation that occurs within the same geographic area of the ancestral species.

Pre-zygotic barrier

A reproductive barrier that prevents mating or fertilization between species.

Post-zygotic barrier

A reproductive barrier that occurs after fertilization, affecting hybrid viability or fertility.

Autopolyploidy

Polyploidy that occurs when a new species forms from a single ancestral species.

Allopolyploidy

Polyploidy that occurs when a new species forms from two different species.

Chromosome number of allopolyploid species

If species A (2n=14) and species B (2n=8) form a new allopolyploid species, its chromosome number is 2n = 22.

Genus

A taxonomic level that groups closely related species.

Macroevolution

The origin of new taxonomic groups (e.g., new species, genera, families) over long periods of time (millions of years).

Continental drift

A large-scale process that causes changes in life on Earth over time.

Mass extinction

A large-scale event that causes the extinction of a significant number of species.

Adaptive radiation

The rapid evolution of many diverse species from a common ancestor, often following a mass extinction or when new niches become available.

Abiotic synthesis

The formation of organic molecules (like amino acids) from non-living matter.

Protocells

Membrane-bound droplets that maintained an internal chemistry, believed to be a step in the origin of life.

LUCA

Last Universal Common Ancestor, the most recent common ancestor of all current life on Earth.

Eons of geological time

The four Eons in order from oldest to most recent are Hadean, Archaean, Proterozoic, Phanerozoic.

First prokaryotes

Appeared during the Archaean Eon.

First eukaryotes

Appeared during the Proterozoic Eon.

Life on land

Began during the Phanerozoic Eon.

Dominant vertebrate group during the Paleozoic Era

Amphibians.

Dominant plant group during the Mesozoic Era

Conifers (Gymnosperms).

Dominant vertebrate group during the Cenozoic Era

Mammals and Birds.

Conditions favoring fossilization

Having hard parts, dying in a place where it gets buried quickly, being an abundant species, and being a long-lived species.

Radiometric dating

Measures the ratio between a radioactive parent isotope and its stable daughter isotope in a rock or fossil.

Major mass extinctions

There have been 5 (or 6, if including the current one) in Earth's history.

Cretaceous mass extinction cause

Believed to be caused by an asteroid impact.

Heterochrony

An evolutionary term describing a change in the rate or timing of developmental events.

Paedomorphosis

The retention of juvenile body features in the adult stage of a descendant.

Homeotic genes

Genes that control the placement and spatial organization of body parts in animals.

Homologous structures

Similar structures shared by different species due to common ancestry, even if they have different functions.

Analogous structures

Structures that have the same function in different species but evolved independently, not from a common ancestor.

Exaptation

A feature that originally evolved under one selective pressure but is later co-opted for a new, different function.

What type of cell membrane is shared by all life that was likely present in LUCA?

A phospholipid bilayer cell membrane

What genetic material is used for genes in all life that was likely present in LUCA?

DNA/RNA

What process do all life forms use to make proteins from the genetic code?

Making proteins from the genetic code

What metabolic process is shared by all life that was likely present in LUCA?

Glycolysis

What molecule is used in metabolism by all life that was likely present in LUCA?

ATP

What is the gel-like substance inside cells that was likely present in LUCA?

Cytoplasm

Hox Gene Cluster

The most significant Homoeotic gene in animals and vertibrates

Hox gene (vertebrates)

became paralogous allowing for more complex forms to develop with novel features forming in the same position on the animal

Convergence

allows organisms to have similar looking features due to adapting to selective pressures, no shared ancestry

Selective pressures

external factor that influences the survival and reproduction, driving natural selection