bio213 chapter 56/29 week 5?

what is extinction?

Complete loss of a species

Natural process

• total extinction, local extinction

• Human activity= major influence

What is genetic diversity?

Variation within and among population

What is species diversity?

Number and variety of species

What is ecosystem diversity?

Variety of habitats and communities

What is conservation biology?

Discipline that integrates ecology, physiology, molecular biology, and evolutionary biology to conserve the diversity of life on earth

What is an endangered species?

A species that is in danger of extinction throughout all or much of its range

What is a threatened species?

A spcies that is likely to become endangered in the near future

What is biophilia?

Human sense of connection to nature and all forms of life

What are the benefits of species and genetic diversity?

1. Medicine

2. Foods/fibers

3. Loss of genetic resources to improve crop qualities

What does a loss of a species entail?

Loss of unique genes that may code for useful proteins

Ex. Taq polymerase → essential for the polymerase chain rxn

What are ecosystem services?

All the processes through which natural ecosystems help sustain human life

• purify air and water

• Detoxify and decompose wastes and reduce impacts of extreme weather and flooding

What is genetic drift?

Frequency of alleles changing (random) over time

Ex. Low genetic diversity→ higher chance of random events impacting the species

What are supporting services?

Ecosystem processes that make other benefits possible

• nutrient cycling

• Water cycling

• Photosynthesis

• Soil formation

What are provisioning benefits?

Material benefits

• food

• Freshwater

• Fiber

• Biomass fuel

• Natural medicine

What are regulating benefits?

Benefits from regulation of ecosystem processes

• air quality

• Water runoff

• Erosion

• Pollination

• Climate

• Natural hazards

What are cultural services?

Non-material benefits

• existence values

• ethical values

• recreation and ecotourism

What are the 4 major threats to biodiversity?

1. Habitat loss

2. Introduced species

3. Overharvesting

4. Global change

What are the effects of habitat loss and fragmentation?

Brought by factors such as agriculture, urban development, forestry, mining, and pollution

1. when no alternative habitat is available or a species is unable to move→ leads to extinction

2. habitat fragmentation→ reduces number of species in a region bc the smaller populations in habitat fragments have a higher probability of extinction

3. loss to aquatic diversity→ coral reefs are lost, freshwater habitats are lost due to dams, reservoirs ,channel modification, and flow regulation

What are the effects of an introduced species?

What are edge effects?

increase in edge around a habitat

What is gene flow?

Two populations sharing genetic information through reproduction

What are the effects of an introduced species?

Sometimes called invasive, non-native, or exotic species→ ones that humans move intentionally/accidentally from the species’ native location

• disrupt new community by preying on native organisms or outcompeting native organisms for resources

What are the effects of overharvesting?

harvesting of wild organisms at rates exceeding the ability of their populations to rebound

• spcies w/ restricted habitats are particularly vulnerable to overharvesting

What are the effects of global change?

1. acid precipitation: rain, snow, fog w/ pH <5.2

• burning of wood and fossil fuels releases oxides of sulfur and nitrogen that react w/ water in air, forming sulfuric and nitric acid

What are the two approaches to conserving population?

1. small-population approach

2. declining-population approach

What is an extinction vortex?

Small population is vulnerable to inbreeding and genetic drift→ draws population down towards smaller and smaller population size, until no individuals survive

• loss of genetic variation in response to new strains of pathogens

What is the positive feedback loop of the extinction vortex?

1. small population→ inbreeding, genetic drift

2. loss of genetic variability—> lower individual fitness and population adaptability

3. lower reproduction, higher mortality→ smaller population

Wht is the minimum viable population (MVP)?

The minimum population size at which a species is able to sustain its numbers

• Dependent on reproductive success, mortality, environmental variability, and genetics

What is the effective population size?

Based on the breeding potential of the population

Ne= 4(Nf*Nm)/Nf+Nm

• MVP is based on effective population size

What are the consequences of loss of habitat to population?

loss of critical habitat can cause threatened and endangered populations to show a downward trend, DESPITE the population being above its MVP

What is the declining population approach?

focuses on why populations are declining (regardless of population size)

• habitat loss, altered disturbance, reduced reproduction, resource limitation

What is landscape ecology?

Conservation happening beyond single populations

• habitat structure, edges, fragmentation, movement between patches

What are edge effects?

Conditions at habitat boundaries that differ from interior habitat

• more wind

• More sunlight

• Different predators

• Invasive species

What are corridors?

Narrow habitat connections between patches

• dispersal

• Migration

• Gene flow

• Inbreeding

What is the critical load?

The amount of added nutrient that can be absorbed by plants without damaging ecosystem integrit

What are endemic species?

Species only found in a spcific area

What are zoned reserves?

Protected natural area

• minimum human disturbance

• buffer zones surround area (limited human activity)

What are examples of urban ecology?

• urban streams

• stormwater runoff

• restoration ecology

• wildlife corridors

What are dead zones?

Result of excess nutrients→ algal bloom→ decomposition→ oxygen depletion

• algal bloom blocks light→ reduces oxygen availability

• results in hypoxia, fish death, biodiversity loss

What is biological magnification?

Toxins increase at higher trophic levels

• highest concetration in top predators

ex. Rodent poison, pharmaceuticals, mercury

What is ozone depletion?

O3 helps block UV radiation

• CFCs→ human-made chemicals braek down ozone molecules

• less ozone= more UV radiation reaches Earth

• can leads to DNA damage, increased skin cancer, damage to plants

Where did plants evolve from?

Evolved from green algae

• charophyte algae

• has cellulose cell walls, similar sperm structure, similar cell division

• plants did not evolve from modern algae

What are the advantages to live on land for plants?

• More access to sunlight

• more CO2

• more available soil nutrients

• less competition early on

What are the disadvantages of living on land?

• risk of drying out

• need for structural support

• reproduction without water

What were major land plant adaptations?

1. cuticle→ reduces water loss

2. stomata→ gas exchange

3. spores→ resistant to drying

4. embryo protection→ offspring survive better

5. apical meristems→ continuous growth

6. mycorrhizae→ improved nutrient uptake

What are spores?

Single reproductive cell (haploid)

• part of reproductive system→ does not fuse with another cell, instead growing into a whole new organism

• resistant to drying out

• helps with dispersal (can travel away from parent plant)

What is a meristem?

A region on plant that cell division occurs

• allows plant to continuously grow

What are mycorrhizae?

Microscopic fungi that help plants with nutrient uptake

What is the alternation of generations?

1. Gametophyte produces haploid gametes by mitosis

2. Two gamets unite and form a diploid zygote

3. the zygote develops into a multicellular diploid sporophyte

4. The sporophyte produces unicellar haploid spores by meiosis

5. The spores develop into multicellular haploid gametophytes

What are embryophytes?

Multicellular, dependent embryo of plants

What is the sporangia?

Mulicellular organ that produces spores

• sporopollenin makes the walls of these spores resistant to harsh environments

What is an apical meristem?

Localized regions of cell division at the tips of roots/shoots

What is the cuticle?

Epidermal covering that consists of wax and other polymers

What is the stomata?

Pores in plants that allow the exchange of CO2 and O2 between outside air and plant

What are non vascular plants (bryophytes)?

1. Phylum hepatophyta (liverworts)

2. Phylum bryophyta (mosses)

3. Phylum anthocerophyta (hornworts)

What are seedless vascular plants?

1. Phylum lycophyta (lycophytes)

2. Phylum monilophyta (monilophytes)

What are gymnosperms?

1. Phylum gingkophyta (ginkgo)

2. Phylum cycadophyta (cycads)

3. Phylum gnetophyta (gnetophytes)

4. Phylum coniferophyta (conifers)

What are angiosperms?

Phylum anthophyta (flowering plants)

What is plant vascular tissue?

Cells joined into tube that transport water and nutrients throughout the plant body

What is a Clade?

Monophyletic group

What is a seed?

Embryo packaged w/ a supply of nutrients inside a protective coat

What are reduced gametophytes?

Microscopic, dependent on sporophyte, and protected inside plant tissue

What does gametophyte dominance indicate?

Sporophyte dominance

What is heterospory?

Seed plants that produce two types of spores

• micro spores, mega spores

What are microspores?

Male spores, become pollen

What are megaspores?

Female, become female gametophyte

• important evolutionary step toward seeds

What is an ovule?

Structure that contains the female gametophyte and egg

What is the megasporangium?

Makes female spores

What is the integument?

Sporophyte tissue that envelops and protects megasporangium

When does an ovule become a seed?

Fertilization

What does each megasporangium contain?

1 megaspore

What does each microsporangium contain?

Contains many microspores

What is an immature ovulate cone?

Structure of ovules that has not been fertilized

What structures of an immature ovulate cone make up the sporophyte?

Integument and megasporangium (2n)

What is the process of fertilization for spore-bearing plants?

1. Pollen grain (n) enters ovule via the micropyle (small opening in the integument)

2. Pollen grain produces a pollen tube that begins growing through the megasporangium→ germination

3. Megaspore matures into female gametophyte (n)

4. When pollen tube reaches the female gametophyte, sperm are discharged from the tube into the female gametophyte

5. Fertilization occurs when the haploid egg nucleus joins with the haploid sperm nucleus, resulting in a fertilized ovule→ prodcues diploid zygote, that undergoes mitosis

6. As embryo develops, the ovule is transformed into seed

7. Female gametophyte become food for embryo

8. The megasporangium shrinks, leaving a remnant that surrounds the spore wall

9. Integument becomes protective seed coat

What is the development of pollen?

1. Microspores develops into a pollen grain (male gametophyte enclosed within the pollen wall)

• wall’s outer layer is made of molecules secreted by sporophyte, so male gametophyte is INSIDE the pollen grain

2. Sporopollenin in the pollen wall protect the grain

3. Pollination occurs when the transfer of pollen is delivered to (an) ovule(s)

What properties do mosses and other non vascular plants have?

Gametophyte: dominant

Sporophyte: reduced, dependent on gametophyte for nutrition

What properties do ferns and other seedless vascular plants have?

Gametophyte: Reduced, independent (photosynthetic and free-living)

Sporophyte: Dominant

What are the properties of gymnosperms and angiosperms?

Gametophyte: Reduced (usually microscopic), dependent on surrounding sporophyte tissue for nutrition

Sporophyte: Dominant

How has miniaturization allowed for evolution in seed plants?

The tiny gametophytes develop from spores retained within the sporangia of the parental sporophyte

• allows for protection of gametophytes from environmental stresses

• Allows for developing gametophytes to obtain nutrients from parental sporophyte

What is a heterosporous plant?

Plant produces two types of spores

• megasporangia on modified leaves called megasporophylls produce megaspores→ female gametophytes

• Microsporangia on modified leaves called microsporophylls produce microspores→ male gametophytes

What is the difference in integument for gymnosperm vs angiosperms?

Gymnosperm: contains 1 layer

Angiosperm: two layers

What are the advantages of spores?

1. Multicellular (consists of an embryo protected by a layer of tissue)

2. Can remain dormant for days, months, years

3. Seeds have a supply of stored food

What are conifers?

Cone-bearing plants such as pines, firs, and redwoods

What is the life cycle of a pine tree?

1. Most conifer species have both ovulate and pollen cones

2. Microsporocytes divide by meiosis, producing haploid microspores. A microspore develops into a pollen grain

3. An ovulate cone scale has two ovules, each containing a megasporangium

4. pollination occurs when a pollen grain reaches the ovule. The pollen grain then germinates, forming a pollen tube that slowly digests its way through the megasporangium

5. While the pollen tube develops, the megasporocyte undergoes meiosis, producing 4 haploid cells→ one survives as a megaspore

6. The megaspore developed into a female gametophyte that contains 2 or 3 archegonia→ each will form an egg

7. When the eggs mature, sperm cells have developed from the pollen tube, which extends from the female gametophyte→ fertilization occurs when sperm and egg nuclei unite

What are the properties of fertilization for a pine tree?

Usually only occurs moer than a year after pollination

• all eggs may be fertilized, but usually only one zygote develops into an embryo

• The ovule becomes a seed, consisting of an embryo, food supply, and seed coat

What are the properties of pollen cones?

Scales are modified leaves (microsporophylls) that bear microsporangia

• within each microsporangium, cells called microsporocytes undergo meiosis, producing haploid microspores

• Each microspore develops into a pollen grain containing a male gametophyte

• in conifers, the yellow pollen is released in large amounts and carried by the wind

What is a bryophyte?

Avascular plant→ mosses, liverworts, hornworts

• small, low-growing, no xylem or phloem

• Requires moist environments

What are mosses?

Dominant gametophyte

• sporophyte attached, depending on gametophyte for nutrients

• Dominant stage→ haploid

• Visible green moss→ gametophyte

What is peat moss?

Stores carbon→ forms peat

What is xylem?

Moves water and minerals upwards from roots

• contains lignin

• Structural support

What is phloem?

Moves sugars throughout plant

What are the properties of ferns?

large leafy fern is sporophyte (2n)

• sporophytes produces spores by meiosis

• Spores grow into tiny heart-shaped gametophyte

• Gametophyte produces egg and sperm

• Fertilization→ new sporophyte

What is the evolution of leaves?

1. Increased surface area

2. Increased photosynthesis→ captures more light

3. Microphylls, megaphylls

What are microphylls?

One vein

What are megaphylls?

Many branched veins

What are sporophylls?

Leaves w/ sporangia

What are sori?

Clusters of sporangia

What are strobili?

Cone-like clusters