Plant Ecology Chapter 7 Growth Reproduction Plant Growth

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Plant Ecology - Chapter 7 Growth & Reproduction

Plant Ecology - Chapter 7 Growth & Reproduction

Plant Growth - Modular

Plant Growth - Modular

Plant Growth - Modular Apical meristems Intercalary meristems Axillary meristems Vascular cambium

Plant Growth - Modular Apical meristems Intercalary meristems Axillary meristems Vascular cambium

Plant Architecture Raunkaier classification system of perennial growth forms >25 cm <25 cm At

Plant Architecture Raunkaier classification system of perennial growth forms >25 cm <25 cm At ground level Below ground level

Plant Architecture Plasticity can change plant shape in response to environmental conditions Sun vs.

Plant Architecture Plasticity can change plant shape in response to environmental conditions Sun vs. shade Self-pruning

Clonal Plants Spatial distribution of ramets affected by: Competition among genets Spatial variation in

Clonal Plants Spatial distribution of ramets affected by: Competition among genets Spatial variation in resource distribution

Clonal Plants Two growth forms Phalanx - tightly grouped advancing front Guerilla - isolated

Clonal Plants Two growth forms Phalanx - tightly grouped advancing front Guerilla - isolated ramets penetrating competitors’ turf All in the perspective

Clonal Plants - Why variation? Mechanics of clonal spread “Foraging” for resources Following the

Clonal Plants - Why variation? Mechanics of clonal spread “Foraging” for resources Following the resource distribution Integration within clone to minimize environmental variation

Vegetative Reproduction Apomixis general term for asexual reproduction Can take on many different forms

Vegetative Reproduction Apomixis general term for asexual reproduction Can take on many different forms

Vegetative Reproduction Stolons - runners - branches that spread at surface of the soil,

Vegetative Reproduction Stolons - runners - branches that spread at surface of the soil, generate new ramets

Vegetative Reproduction Rhizomes underground horizontal stems growing near soil surface Many grasses (like bamboo)

Vegetative Reproduction Rhizomes underground horizontal stems growing near soil surface Many grasses (like bamboo)

Vegetative Reproduction Bulbs underground rosette stems that store nutrients Tulips, onions, daffodils

Vegetative Reproduction Bulbs underground rosette stems that store nutrients Tulips, onions, daffodils

Vegetative Reproduction Suckers - bud formation on some of nearsurface roots Quaking aspen clones

Vegetative Reproduction Suckers - bud formation on some of nearsurface roots Quaking aspen clones can cover many hectares

Vegetative Reproduction Clonal fragmentation pieces break off, are capable of rooting to form new

Vegetative Reproduction Clonal fragmentation pieces break off, are capable of rooting to form new plants Mother of thousands

Vegetative Reproduction Bulbils - bulblike organs produced in leaf axils

Vegetative Reproduction Bulbils - bulblike organs produced in leaf axils

Seeds Produced Asexually Agamospermy partial meiosis without reduction division - new embryos are clones

Seeds Produced Asexually Agamospermy partial meiosis without reduction division - new embryos are clones

Seeds Produced Asexually Grasses, raspberries, nettles

Seeds Produced Asexually Grasses, raspberries, nettles

Sexual Life Cycles Alternation of generations Gametophyte Sporophyte Lower plants gametophyte dominant Higher plants

Sexual Life Cycles Alternation of generations Gametophyte Sporophyte Lower plants gametophyte dominant Higher plants sporophyte dominant

Pollination Ecology Pollination of typical, showy flowers done by birds or insects But many

Pollination Ecology Pollination of typical, showy flowers done by birds or insects But many flowers not showy, and likely are pollinated by wind

Pollination Ecology Pollen transfer in most grasses and temperate-zone trees is by wind Human

Pollination Ecology Pollen transfer in most grasses and temperate-zone trees is by wind Human allergies to pollen (hay fever) due to huge amounts of pollen in air

Pollination Ecology Wind-pollinated flowers are not showy Waste of energy to produce big, colorful

Pollination Ecology Wind-pollinated flowers are not showy Waste of energy to produce big, colorful petals, scents, nectar Grasses often lack petals, sepals (interfere with pollen transfer by wind)

Pollination Ecology Wind-pollinated plants produce massive quantities of pollen Little influence over where pollen

Pollination Ecology Wind-pollinated plants produce massive quantities of pollen Little influence over where pollen goes

Pollination Ecology Wind-pollinated plants have higher pollen: ovule ratios than their animalpollinated relatives

Pollination Ecology Wind-pollinated plants have higher pollen: ovule ratios than their animalpollinated relatives

Pollination Ecology Wind pollination most common in plants of open habitats Usually flower before

Pollination Ecology Wind pollination most common in plants of open habitats Usually flower before leaves emerge in spring Also windiest time of year Pollen can travel 100 s of miles

Pollination Ecology Wind pollination might be evolutionarily primitive But wind pollination is common in

Pollination Ecology Wind pollination might be evolutionarily primitive But wind pollination is common in both “old” and “new” taxa Both can be present in same group

Visual Displays Flower shape and color are advertisements of the rewards an animal can

Visual Displays Flower shape and color are advertisements of the rewards an animal can expect to receive from the flower But both sides cheat

Visual Displays Insects usually see colors at shorter wavelengths than humans (e. g. ,

Visual Displays Insects usually see colors at shorter wavelengths than humans (e. g. , ultraviolet) Birds more sensitive to colors in middle and red parts of spectrum Birds may not see or be attracted to flowers bees can see

Visual Displays Many bee-pollinated flowers are yellow Bird-pollinated flowers often orange or red Moths:

Visual Displays Many bee-pollinated flowers are yellow Bird-pollinated flowers often orange or red Moths: white to pale yellow Bats: white to brown

Visual Displays Some flowers reflect light in several different wavelengths - can be seen

Visual Displays Some flowers reflect light in several different wavelengths - can be seen by different pollinators Contrasting colors may help guide pollinator - nectar guide

Visual Displays Some plants have modified other plant parts to attract pollinators Poinsettias -

Visual Displays Some plants have modified other plant parts to attract pollinators Poinsettias - red bracts, leaves more attractive than small, yellow flowers

Visual Displays Some plants arrange flowers into various aggregations inflorescences Increase the size of

Visual Displays Some plants arrange flowers into various aggregations inflorescences Increase the size of the attractive display without altering the flowers themselves

Floral Odors Scents act as attractants over longer distances than visual attractants First locate

Floral Odors Scents act as attractants over longer distances than visual attractants First locate generally by scent, then locate specifically by sight

Floral Odors can vary independently of colors Odors of different species can be highly

Floral Odors can vary independently of colors Odors of different species can be highly variable, to attract different pollinators

Floral Odors Bees attracted to sweet odors (like we are) Bats like musty odors

Floral Odors Bees attracted to sweet odors (like we are) Bats like musty odors Flies like rotting flesh and dung odors

Restricting Visitors Adaptations to attract right visitor, repel unwanted visitors Change flower shape from

Restricting Visitors Adaptations to attract right visitor, repel unwanted visitors Change flower shape from unspecialized bowl to something else Only long tongues/mouthparts can access rewards

The Reward Usually nectar (sugars) or pollen (protein) Can also be oils, scent Timing

The Reward Usually nectar (sugars) or pollen (protein) Can also be oils, scent Timing of reward also changeable (day vs. night) Nectar robbers

Pollination Syndromes Certain combinations of flower color, shape, odor, reward type, timing of rewards

Pollination Syndromes Certain combinations of flower color, shape, odor, reward type, timing of rewards often associated with certain types of pollinators Tightly coevolved mutualisms

Pollination Syndromes Bee-pollinated flowers - yellowish, sweetsmelling, broad to allow bee contact with anthers,

Pollination Syndromes Bee-pollinated flowers - yellowish, sweetsmelling, broad to allow bee contact with anthers, stigma, produce nectar during daytime

Pollination Syndromes Bird-pollinated flowers - red or orange, little scent, produce lots of nectar

Pollination Syndromes Bird-pollinated flowers - red or orange, little scent, produce lots of nectar during the day, shape with long tubes or spurs

Pollination Syndromes Strength, generality of pollination syndromes may be overstated Syndromes are tendencies rather

Pollination Syndromes Strength, generality of pollination syndromes may be overstated Syndromes are tendencies rather than laws Animals “outside” syndrome can accomplish significant pollination

Pollination Syndromes emphasize specialist pollinators, but neglect the generalist pollinators, which may be more

Pollination Syndromes emphasize specialist pollinators, but neglect the generalist pollinators, which may be more important

Complex Interactions! St. Johnswort on shores of Florida ponds Plants growing by fishfree ponds

Complex Interactions! St. Johnswort on shores of Florida ponds Plants growing by fishfree ponds more pollenlimited than those around fish ponds

Aquatic Pollinators? Most aquatic plants bear flowers above water surface Plants pollinated by insects

Aquatic Pollinators? Most aquatic plants bear flowers above water surface Plants pollinated by insects or wind

Aquatic Pollinators? Large numbers of aquatic plants have underwater flowers One strategy: make pollen

Aquatic Pollinators? Large numbers of aquatic plants have underwater flowers One strategy: make pollen dispersal units bigger, disperse/receive at surface (Vallisneria) Others: sticky pollen in rafts, elongated pollen

Plant Mating Systems Factors that govern who can mate with whom Many complications because

Plant Mating Systems Factors that govern who can mate with whom Many complications because of widely varying gender expression

Plant Mating Systems Obligatory selffertilization - inbreeding - individuals can only pollinate themselves Outcrossing

Plant Mating Systems Obligatory selffertilization - inbreeding - individuals can only pollinate themselves Outcrossing mechanisms preventing self-fertilization Something in between

Gender Issues Some individual plants are cosexual - function as both males and females

Gender Issues Some individual plants are cosexual - function as both males and females simultaneously Hermaphroditism - most common type of gender expression in plants Individuals have perfect flowers containing both functional stamens and functional stigmas

Monoecy Individual plants have some flowers with functional stamens only (staminate flowers) and some

Monoecy Individual plants have some flowers with functional stamens only (staminate flowers) and some with functional stigmas only (pistillate flowers)

Monoecy All individuals have both types of flowers

Monoecy All individuals have both types of flowers

Monoecy

Monoecy

Dioecy At least some plants in a population have only pistillate or only staminate

Dioecy At least some plants in a population have only pistillate or only staminate flowers Function as female only or male only

Mixed gender expression 3 systems of gender expression can exist in combination with one

Mixed gender expression 3 systems of gender expression can exist in combination with one another E. g. , gynomonoecy, androdioecy

Mixed gender expression Sequential hermaphroditism often begin life as male, then gradually switch to

Mixed gender expression Sequential hermaphroditism often begin life as male, then gradually switch to female

Self-fertilization Cosexual plants may or may not be capable of selffertilization 25% of windpollinated

Self-fertilization Cosexual plants may or may not be capable of selffertilization 25% of windpollinated cosexual plants are mainly inbreeding remainder strongly outcrossing

Self-fertilization Animal-pollinated cosexual plants evenly divided among strongly inbreeding, strongly outcrossing, and mixtures of

Self-fertilization Animal-pollinated cosexual plants evenly divided among strongly inbreeding, strongly outcrossing, and mixtures of inbreeding and outcrossing

Confusion Different forms of gender expression can occur at same time within a population

Confusion Different forms of gender expression can occur at same time within a population Difficult to determine how they actually function

Competition for Pollinators & Pollen Plants produce excess ovules that never produce viable seeds

Competition for Pollinators & Pollen Plants produce excess ovules that never produce viable seeds Competition for pollinators, pollen? Too few pollinators, or very inefficient at transferring pollen

Sexual Selection Differential success at mating among plants Male-to-male competition Female choice

Sexual Selection Differential success at mating among plants Male-to-male competition Female choice

Sexual Selection Male-to-male competition results in extremes of floral displays Large inflorescences where most

Sexual Selection Male-to-male competition results in extremes of floral displays Large inflorescences where most flowers function only to attract pollinators Functionally male reproduce only by having pollen taken elsewhere

Sexual Selection Female choice occurs at site of pollination Competition among pollen grains Female

Sexual Selection Female choice occurs at site of pollination Competition among pollen grains Female flower “chooses” pollen via biochemical interactions Affect pollen germination, rate of pollen tube growth May selectively abort certain seeds

Pollen Dispersal Inbreeding common in plants Most matings occur among neighbors, which tend to

Pollen Dispersal Inbreeding common in plants Most matings occur among neighbors, which tend to be relatives

Pollen Dispersal Animal-pollinated plants Plants are clumped, pollinators don’t move much

Pollen Dispersal Animal-pollinated plants Plants are clumped, pollinators don’t move much

Pollen Dispersal Wind-pollinated plants Most pollen grains fall nearest their source Plants releasingle pollen

Pollen Dispersal Wind-pollinated plants Most pollen grains fall nearest their source Plants releasingle pollen grains most likely to mate with most distant individuals Clumped pollen - mating with nearest neighbors

Assortative Mating Plants with similar phenotypes mate with one another more often than they

Assortative Mating Plants with similar phenotypes mate with one another more often than they would by chance Time of flowering, flower color, influence the pollinator

Negative Assortative Mating Plants with dissimilar phenotypes mate with one another more often than

Negative Assortative Mating Plants with dissimilar phenotypes mate with one another more often than they would by chance Heterostyly styles/stigmas of different lengths cause obligate outcrossing

Fruits and Seeds Fruit - mature ovary with seeds - great variety Two functions

Fruits and Seeds Fruit - mature ovary with seeds - great variety Two functions protect developing seeds, affect dispersal of seeds

Fruits and Seeds Compromise between protecting seeds from being eaten, and attracting animal consumers

Fruits and Seeds Compromise between protecting seeds from being eaten, and attracting animal consumers to aid in seed dispersal

Fruits and Seeds Wind dispersal - float, flutter based on mass, surface area, shape

Fruits and Seeds Wind dispersal - float, flutter based on mass, surface area, shape

Fruits and Seeds Animal dispersal attract/reward disperser, but protect seeds Thick, hard seed coats

Fruits and Seeds Animal dispersal attract/reward disperser, but protect seeds Thick, hard seed coats Spit out, regurgitated, pass with feces

Seed Banks Dispersal in time Seedbank - collection of seeds in the soil Short-lived

Seed Banks Dispersal in time Seedbank - collection of seeds in the soil Short-lived plants tend to have long-lived seeds, and vice versa