BIOL 208 - Exam #1

Ecosystem services

the direct and indirect benefits that humans get from healthy natural environments and functioning ecological systems

ecosystem functions

the biological, geochemical, and physical processes that take place within an ecosystem to sustain its structure and integrity

Roots

vegetative structure, the underground organ of a plant that absorbs water and minerals and holds the plant in the ground

Shoots

the above-ground part of a vascular plant that consists of the stem, leaves, buds, flowers, and fruits

Vascular system

a network of tubes and vessels that transports fluids, nutrients, gases, and wastes throughout the body of an animal or a plant

Xylem

Tissue that transports water and dissolved minerals upward from the roots to the leaves.

Phloem

Tissue that conducts sugars and food produced by photosynthesis from the leaves to the rest of the plant

Meristems

a type of plant tissue made up of undifferentiated, actively dividing cells that allow a plant to grow throughout its entire life

Flowers

the seed-bearing part of a plant, consisting of reproductive organs (stamens and carpels) that are typically surrounded by a brightly coloured corolla (petals) and a green calyx (sepals)

pollen

a fine powdery substance, typically yellow, consisting of microscopic grains discharged from the male part of a flower or from a male cone. Each grain contains a male gamete that can fertilize the female ovule, to which pollen is transported by the wind, insects, or other animals

ovule

the part of the ovary of seed plants that contains the female germ cell and after fertilization becomes the seed

sessile

fixed in one place; immobile

modular growth

a growth strategy in which an organism increases in size or complexity by repeatedly adding self-contained, structurally similar units (modules) rather than by continuous, linear extension of a single structure - integrate colonial organisms tht grow and produce new organs throughout their life

meristems

a region of plant tissue, found chiefly at the growing tips of roots and shoots and in the cambium, consisting of actively dividing cells forming new tissue

Photosynthesis

process by which green plants and other organisms transform lighter energy into chemical energy

germ cells

a cell containing half the number of chromosomes of a somatic cell and able to unite with one from the opposite sex to form a new individual; a gamete

somatic cells

any cell in the body that are not the gametes

Evolutionary change

the modifications in inherited traits of populations over successive generations, driven by mechanisms such as natural selection, mutation, genetic drift, and gene flow, resulting in the diversity of life observed today. - change in allele frequency in a population

Phenotype

the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

 (P = G + E), Heritable,  Differential survival/reproduction

Natural selection

the process whereby organisms better adapted to their environment tend to survive and produce more offspring

mechanism of evolutionary change, → phenotypic variation, variation is heritable, differential survivial/reproduction

Local adaptation

Occurs due to genetic change where individuals from a population have higher average fitness in their local region

Relative fitness

a measure of how well a genotype or phenotype reproduces compared to the most successful genotype or phenotype in a population.

the number of genes contributed to the next generation relative to other individuals in the population

Ecotypes

a genetically distinct population or variety within the same species that has adapted to specific local environmental conditions

genetically differentiated groups of plants that are locally adapted to different environmental conditions

Plasticity

the adaptability of an organism to changes in its environment or differences between its various habitats

when environmental factors can cause plants with the same genotype to have very different morphologies

Genetic Drift

random change in allele frequency over time

Founder effect

what happens when a small group splits off from a larger population and starts a new one, carrying only a fraction of the original group’s genetic diversity. Because these few individuals can’t represent the full genetic range of the population they came from, their descendants end up with a narrower genetic profile, sometimes dramatically so…

Bottleneck

when a significant event drastically reduces the number of individuals within a species. The surviving population carries only a fraction of the original genetic diversity. This reduction happens because many individuals and their unique alleles are lost randomly during the population crash

Gene flow

the introduction of genetic material (by interbreeding) from one population of a species to another, thereby changing the composition of the gene pool of the receiving population

mitosis

a process of nuclear division in eukaryotic cells where the duplicated chromosomes are separated and distributed into two daughter nuclei. It takes place in the M phase of cell cycle. Before, DNA has already been replicated during S phase, so the replicated chromosome at this time consists of two sister chromatids.

The sister chromatids are arranged with the help of mitotic spindle. These are then separated and move towards the opposite poles. This gives an equivalent set of chromosomes to each daughter nucleus

meiosis

specialized type of cell division in germ cells that consists of two successive nuclear divisions, producing four genetically distinct haploid cells (gametes, or sex cells), each possessing half the number of chromosomes of the original diploid cell

Haploid

(of a cell or nucleus) having a single set of unpaired chromosomes

Diploid

(of a cell or nucleus) containing two complete sets of chromosomes, one from each parent

Chromosome

a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

chromatid

condensed chromosomes distinguishable during cell division. Those that are joined together at the centromere and carry identical copies of DNA molecules

Homologous chromosomes

pairs of chromosomes that have the same genes in the same order, though the specific versions of those genes (alleles) may differ. One chromosome in each pair is inherited from each parent

Prophase

the first stage of cell division, before metaphase, during which the chromosomes become visible as paired chromatids and the nuclear envelope disappears. The first prophase of meiosis includes the reduction division

Metaphase

the second stage of cell division, between prophase and anaphase, during which the chromosomes become attached to the spindle fibers

Anaphase

in mitosis and meiosis, the stage of cell division in which separated chromatids (or homologous [like] chromosome pairs, as in the first meiotic division) move toward the opposite poles of the spindle apparatus

Telophase

the final phase of cell division, between anaphase and interphase, in which the chromatids or chromosomes move to opposite ends of the cell and two nuclei are formed

Cytokinesis

the cytoplasmic division of a cell at the end of mitosis or meiosis, bringing about the separation into two daughter cells

Biological species concept

defines a species as a group of natural populations that can interbreed and produce fertile offspring while being reproductively isolated from other such groups

Asexual reproduction

a type of reproduction that does not entail the union of sex cells or gametes. Unlike in sexual reproduction wherein male and female gametes unite to reproduce offspring, in this reproduction, this union is not necessary. The organism can reproduce in the absence of a mate which, in this case, produces offspring which is usually a clone of the parent.

Hybridization

describes the process of combining two different components to create a new entity. In biology, this specifically refers to the mixing of genetic material from distinct sources

Morphological species concept

defines a species based on shared physical characteristics or morphology, grouping organisms that exhibit significant similarity in observable traits.

Ecological species concept

defines a species as a group of organisms that occupy a specific ecological niche and are adapted to a particular set of environmental conditions.

Phylogenetic species concept

defines a species as the smallest diagnosable cluster of organisms that share a common evolutionary ancestry and form a distinct, monophyletic lineage.

Allopatric speciation

speciation that happens when two populations of the same species become isolated from each other due to geographic changes. Speciation is a gradual process by which populations evolve into different species. A species is itself defined as a population that can interbreed, so during speciation, members of a population form two or more distinct populations that can no longer breed with each other.

Reproductive isolating mechanisms

mechanisms prevent gene flow between populations, thereby maintaining the distinctiveness of species. Reproductive isolating mechanisms are broadly categorized into two types: prezygotic and postzygotic. Each type plays a unique role in preventing interbreeding and ensuring reproductive isolation

Sympatric speciation

an evolutionary process where new species evolve from a single ancestral species while inhabiting the same geographic region, without any physical or spatial barriers separating them

Polyploidy

a genetic condition where a cell or organism has more than two complete sets of chromosomes

Nondisjunction

the failure of paired chromosomes or sister chromatids to separate properly during cell division, leading to daughter cells with an abnormal number of chromosomes.

Absence of cytokinesis

a cell's nucleus divides through mitosis, but the cytoplasm fails to split, resulting in a single cell with multiple nuclei (known as a multinucleated cell or a syncytium)

Tetraploid, Triploid, Hexaploid…

a condition where an organism has more than two complete sets of chromosomes in its cells

Autopolyploidy

a condition where an organism has more than two complete sets of chromosomes, and all of those chromosome sets come from the same species

Allopolyploidy

a condition where an organism has more than two sets of chromosomes that come from two or more different parent species

Role of polyploidy in domestication of plants

having more than two complete sets of chromosomes—is a major driver of agronomic traits, gigantism, and evolutionary novelty that humans selectively targeted during plant domestication

Recombination speciation

an evolutionary process where a new species arises from the hybrid offspring of two different species, possessing a unique combination of parental chromosomes that prevents them from successfully interbreeding with either parent group.

Phylogeny

the evolutionary history and development of a species or a group of organisms

Common ancestor

an ancestral group, population, or species shared by two or more descendant lineages

Ancestral traits

a physical, behavioral, or genetic feature passed down from a common ancestor to a group of descendant species

Derived traits

a physical, genetic, or behavioral characteristic that has evolved from an ancestral form and appears in a later lineage or species

Homologous traits

physical or genetic features in different organisms that share a common evolutionary origin and ancestor, even if they now serve different functions.

Shared derived trait

a specific physical or genetic characteristic that evolved in a recent common ancestor and is passed down to all of its descendants within a group (clade), but is absent in more distant ancestors

Outgroup

is a more distantly related group of organisms used as a reference point to root a phylogenetic tree or cladogram and determine the evolutionary relationships of the ingroup (the set of organisms actually being studied). [1]

Parsimony

the rule that the simplest explanation requiring the fewest evolutionary changes is the most likely to be correct

Convergent evolution

an evolutionary process where unrelated or distantly related organisms independently develop similar traits, features, or behaviors because they adapt to similar environmental pressures or ecological niches.

Reversals

a change or evolutionary process where a lineage or organism returns to a state resembling an ancestral trait or condition

Monophyletic

a collection of organisms that includes a single common ancestor and all of its descendants

Paraphyletic

a collection of organisms that includes a common ancestor and some, but not all, of that ancestor's descendants.

Polyphyletic

a collection of organisms that are grouped together based on shared physical traits or habits, but do not share a recent common ancestor

Evolution of autotrophs

evolved from primitive anaerobic organisms that harnessed inorganic chemicals or light to fix carbon dioxide, laying the foundation for all complex life on Earth

Transition to Land

one of the most significant evolutionary events in biology, requiring major shifts in how organisms breathe, move, reproduce, and handle dehydration.

Adaptations to land

structural, physiological, and reproductive adaptations to transition from aquatic environments to land - Roots, vascular tissue, reduced water loss

Turgor pressure

The outward hydrostatic force that internal water exerts against a cell's plasma membrane and rigid cell wall

• increases stiffness of plant cells

• water moves into the cell via osmosis

• creates pressure on the rigid cell wall

• causes pressure, stiffening the cell and supporting non-woody plant parts

• water moving out of the cell causes wilting due to loss of ““ pressure

Lignin

a complex organic polymer that hardens plant cell walls, providing structural support and waterproofing for vascular plants

• supports the plant, allowing it to get tall and develop large branches

• second most abundant organic compound on earth and is very difficult to break down

• waterproofs the cells, assisting water transport in xylem

• Lignin is also deposited in response to attack by fungi

Transition to land

• Presented new challenges

• Very different abiotic conditions and limiting resources —> minerals in aquatic environments are hard to find, and water in terrestrial environments)

• Water also no longer provides structural support

• Land plants evolved from a group of green algae (in the zygnematophyceae

• Green algae are found in most aquatic ecosystems as well as in most terrestrial habitats

• Horizontal gene transfer between the green algae and soil bacteria 580 mya

• provided genes that give resistance to desiccation and other stressors

• transformed the surface of the planet —> increased energy budget, atmospheric chemistry, biogeochemical cycles, habitats for others

adaptations to land

• Changes that allowed plants to utilize novel habitats on land:

  • water uptake and transport: roots and vascular tissue

  • Reduce water loss: multicellularity (lower surce: volume ratio), cuticle, stomata, protected embryos

• Expansions to gene families correlated with evolutionary innovation:

  • gene duplication is associated with the origin of green plants, land plants, and vascular plants

  • polyploidy is associated with the evolution of ferns and flowering plants

Bryophytes

ex: mosses, hornworts

Ancestral Traits

• haploid life stage dominant

• fertilization requires water

• reproduction via spores

Derived Traits

• have a cuticle, stomata to reduce water loss

Fern

ex: horsetail

Ancestral Traits

• Fertilization requires water

• Reproduction via spores

• have a cuticle, stomata

Derived Traits

• diploid life stage dominant

• Xylem/phloem

• true leaves and roots

• lignin

Gymnosperms

ex: conifers, cycads, ginkgo

Ancestral Traits

• cuticle, stomata

• diploid life stage dominant

• true leaves, roots

• Xylem/phloem

• lignin

Derived Traits

• fertilization does not require water

• reproduction via seeds

angiosperm

ex: American chestnut, purple loosestrife

Ancestral Traits

• cuticle, stomata

• diploid life stage dominant

• true leaves and roots

• Xylem/phloem

• lignin

• fertilization does not require water

• reproduction via seeds

Derived Traits

• flowers!

Rhynia

• Early seedless vascular plant

• no leaves

• no roots

• cuticle

• xylem with lignin

• supported by turgor pressure

lepidodendron

fossil lycophytes

• scale-like leaves

• rhizophores

• could add xylem cells

• thick bark-like layer on outside for support

• anchored by underground horizontal stems

• 35-40 m tall

• reproduced via spores

• one of most common plants during their time (could add extra xylem to get more thickness)

• 
  

sigillaria

fossil lycophytes

• live in flood plains

• have longer microfils

• short life cycle

calamite

Fossil horsetails

• hollow trunk

• bulkheads to add strength

• underground rhizomes with true roots

• 20-30 m tall

• reproduced via spores (no seeds)

psaronius

fossil ferns

• trunk made up of leaf bases and aerial roots

• reproduced via spores, not seeds

• xylem and phloem don’t increase trunk

• convergent evolution of tree growth form

microphylls

Evolution of leaves in fossil lycophytes

• secondary growth in lycophytes: can’t increase the number of cells in diameter, limited growth in circumference

progoymnosperms

Secondary growth and the bifacial cambium

• able to increase in diameter by cell division within the cambium layer

• trees can grow fast and thin, thicken later for strength and stability

• can make new xylem every year

• easy, fast branching

pioneer species

sun species

ex: sweet birch

• many species germinate after a disturbance

• herbaceous species dominate first

• tree seedlings take longer to get tall but eventually outcompete other species

climax species

shade-tolerant species

ex: American beech

• Other tree species are shade-tolerant, grow slowly, and will eventually outcompete pioneer tree species

emergent trees

• Tallest trees emerge from the canopy below

• water availability limits the number of leaves and size of the canopy; wind exposure dries out the leaves, increases drag and risk of breakage

• small, rollable leaves with flexible stems

• strongly anchored to the soil

canopy trees

• form a canopy of leaves

• shade tolerant

• monolayer of leaves

• slow growing

• durable, dense wood

• chemical defenses

• against insects and fungi

• long lived

understory trees

• under the canopy

• deep shade

• very shallow monolayer of leaves

• very slow-growing

• very dense wood

• heavily defended against fungi and insects

gap/sun species

• Sun species can colonize gaps in the canopy

• multilayer canopy

• fast growing

• lightweight wood (cheap to make)

• few defensive chemicals (cheap to make)

tropical rainforests

• no seasons

• less wind

• plenty of moisture

• thin bark, buttresses

• chemical defensives

• evergreen leaves, drip tips

• animal pollinated, dispersed

temperate deciduous forests

• more wind, distinct growing seasons

• more wind, dispersed pollen and seeds, wind-resistant trunks

• drop leaves during winter ‘drought’

boreal forests

• short summers

• winder droughts

• dominated by conifers

• tracheids are more tolerant of embolisms

• keep leaves over the winter to conserve resources and to maximize use of short growing season

• frost- and drought-tolerant needles

woody vines

• non-self-supporting structural parasites —> vine growth form has evolved independently many times

• some are herbaceous

• produce very long stems, allowing them to access light without investing energy in growing their own structural support

• allocate more resources to leaves, resulting in greater photosynthetic area

• develop a deeper, more extensive root system, as the roots do not need to anchor/stabilize a large trunk

• often associated with gaps and edges

• vines can climb up to the top of the canopy to exploit high light levels

• can create multiple canopies by climbing up more than one tree

• compete with trees, can cause physical damage to tree’s increase risk of wind damage, stall canopy gap regeneration

• Found in the tropics and temperate forests and have evolved many ways to climb a tree

life history strategies

variation among species in how resources are allocated

• number vs. size of offspring

• annual vs perennial (reproduction vs. adult survival)

  • low adult survival rate: reproduce early, high reproductive effort —> annuals: all energy goes into reproduction

  • low juvenile survival rate: reproduce later, more resources to adult survival —> perennials: energy into both reproduction and parent survival, produce seeds over multiple years

• timing of first reproduction (early vs. wait)

  • birch trees —> produce many seeds early

  • beech trees —> produce few seeds later

r and K selection

describes how species evolve different strategies for reproduction, growth, and survival based on their environment. The terms come from population ecology equations, where ““ stands for the intrinsic growth rate of a population and ““ stands for the carrying capacity of the environment

““-selected species focus on a high growth rate and rapid reproduction. They do best in unstable, unpredictable, or disturbed environments where individuals face high, random mortality

““-selected species focus on living at or near the carrying capacity of a stable environment. They do best in crowded niches where strong competition for limited resources dictates survival