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What makes a species invasive?. What makes a species invasive?. An observation: “Tens Rule” From Williamson & Fitter (1996) Ecology 77:1661-1666. What makes a species invasive?. An observation: “Tens Rule” From Williamson & Fitter (1996) Ecology 77:1661-1666
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What makes a species invasive? • An observation: • “Tens Rule” From Williamson & Fitter (1996) Ecology 77:1661-1666
What makes a species invasive? • An observation: • “Tens Rule” From Williamson & Fitter (1996) Ecology 77:1661-1666 • Only ~10% of imported species escape to wild
What makes a species invasive? • An observation: • “Tens Rule” From Williamson & Fitter (1996) Ecology 77:1661-1666 • Only ~10% of imported species escape to wild • Of species that make it to the wild, only ~10% become naturalized
What makes a species invasive? • An observation: • “Tens Rule” From Williamson & Fitter (1996) Ecology 77:1661-1666 • Only ~10% of imported species escape to wild • Only ~10% of species that make it to the wild become naturalized • Of species that become naturalized, only ~10% become pests
What makes a species invasive? • An observation: • “Tens Rule” From Williamson & Fitter (1996) Ecology 77:1661-1666 • Only ~10% of imported species escape to wild • Only ~10% of species that make it to the wild become naturalized • Only ~10% of naturalized species become pests
What makes a species invasive? • An observation: • “Tens Rule” From Williamson & Fitter (1996) Ecology 77:1661-1666 • Only ~10% of imported species escape to wild • Only ~10% of species that make it to the wild become naturalized • Only ~10% of naturalized species become pests • Example: • 1000 imported species
What makes a species invasive? • An observation: • “Tens Rule” From Williamson & Fitter (1996) Ecology 77:1661-1666 • Only ~10% of imported species escape to wild • Only ~10% of species that make it to the wild become naturalized • Only ~10% of naturalized species become pests • Example: • 1000 imported species • 100 escape to wild
What makes a species invasive? • An observation: • “Tens Rule” From Williamson & Fitter (1996) Ecology 77:1661-1666 • Only ~10% of imported species escape to wild • Only ~10% of species that make it to the wild become naturalized • Only ~10% of naturalized species become pests • Example: • 1000 imported species • 100 escape to wild • 10 become naturalized
What makes a species invasive? • An observation: • “Tens Rule” From Williamson & Fitter (1996) Ecology 77:1661-1666 • Only ~10% of imported species escape to wild • Only ~10% of species that make it to the wild become naturalized • Only ~10% of naturalized species become pests • Example: • 1000 imported species • 100 escape to wild • 10 become naturalize • 1 becomes pest
What makes a species invasive? • An observation: • “Tens Rule” From Williamson & Fitter (1996) Ecology 77:1661-1666 • Only ~10% of imported species escape to wild • Only ~10% of species that make it to the wild become naturalized • Only ~10% of naturalized species become pests • Example: • 1000 imported species • 100 escape to wild • 10 become naturalize • 1 becomes pest • If so few species become invasive, does a plant species • become invasive because it has certain characteristics?
What makes a species invasive? • Species characteristics: • Nevada’s Coordinated Invasive Weed Strategy: Invasive weeds often share characteristics such as: • Highly competitive Cause environmental degradation • Exotic Easily spread • Highly aggressive Are difficult to control • Cause economic loss Augment wildfires • Davis & Thompson (2000): 8 ways to be a colonizer, but only 2 ways to be an invader • Richardson et al. (2000): Invasive plants are naturalized plants that produce reproductive offspring (often in large numbers) at considerable distance from parent plants
What makes a species invasive? • Species characteristics: Plant Life History Traits (Chapter 3 of NRC 2002) • Reproductive system • Dioecious (male & female flowers on separate plants) vs. Monoecious (on same plant)
What makes a species invasive? • Species characteristics: Plant Life History Traits (Chapter 3 of NRC 2002) • Reproductive system • Dioecious vs. Monoecious • Self-incompatible pollen vs. Self-compatible pollen
What makes a species invasive? • Species characteristics: Plant Life History Traits (Chapter 3 of NRC 2002) • Reproductive system • Dioecious vs. Monoecious • Self-incompatible pollen vs. Self-compatible pollen • Some type of asexual reproduction • Apomixis – produce viable seed without fertilization • Vegetative reproduction – regenerate from stem or root fragments • Clonal propogation – new individuals produced through rhizomes
What makes a species invasive? • Species characteristics: Plant Life History Traits (Chapter 3 of NRC 2002) • Reproductive system (tend to be: self-compatible monoecious w/ asexual reproduction)
What makes a species invasive? • Species characteristics: Plant Life History Traits (Chapter 3 of NRC 2002) • Reproductive system (tend to be: self-compatible monoecious w/ asexual reproduction) • Flowering & fruiting periods • Short vs. Long flowering period
What makes a species invasive? • Species characteristics: Plant Life History Traits (Chapter 3 of NRC 2002) • Reproductive system (tend to be: self-compatible monoecious w/ asexual reproduction) • Flowering & fruiting periods • Short vs. Long flowering period • Short vs. Long fruiting period
What makes a species invasive? • Species characteristics: Plant Life History Traits (Chapter 3 of NRC 2002) • Reproductive system (tend to be: self-compatible & monoecious w/ asexual reproduction) • Flowering & fruiting periods (tend to be: long) • Juvenile period • Short vs. long
What makes a species invasive? • Species characteristics: Plant Life History Traits (Chapter 3 of NRC 2002) • Reproductive system (tend to be: self-compatible & monoecious w/ asexual reproduction) • Flowering & fruiting periods (tend to be: long) • Juvenile period (tend to be: short) • Seed production • Low vs. high
What makes a species invasive? • Species characteristics: Plant Life History Traits (Chapter 3 of NRC 2002) • Reproductive system (tend to be: self-compatible & monoecious w/ asexual reproduction) • Flowering & fruiting periods (tend to be: long) • Juvenile period (tend to be: short) • Seed production (tend to be: high) • Germination cues • Present vs. Absent
What makes a species invasive? • Species characteristics: Plant Life History Traits (Chapter 3 of NRC 2002) • Reproductive system (tend to be: self-compatible & monoecious w/ asexual reproduction) • Flowering & fruiting periods (tend to be: long) • Juvenile period (tend to be: short) • Seed production (tend to be: high) • Germination cues (tend to be: present) • Light requirements • Low vs. High ability to capture and efficiently use
What makes a species invasive? • Species characteristics: Plant Life History Traits (Chapter 3 of NRC 2002) • Reproductive system (tend to be: self-compatible & monoecious w/ asexual reproduction) • Flowering & fruiting periods (tend to be: long) • Juvenile period (tend to be: short) • Seed production (tend to be: high) • Germination cues (tend to be: present) • Light requirements • Low vs. High ability to capture and efficiently use • High phenotypic plasticity for light & other resources
What makes a species invasive? • Species characteristics: Plant Life History Traits (Chapter 3 of NRC 2002) • Reproductive system (tend to be: self-compatible & monoecious w/ asexual reproduction) • Flowering & fruiting periods (tend to be: long) • Juvenile period (tend to be: short) • Seed production (tend to be: high) • Germination cues (tend to be: present) • Light requirements • Low vs. High ability to capture and efficiently use • High phenotypic plasticity for light & other resources • High competitive ability for light & other resources
What makes a species invasive? • Species characteristics: Plant Life History Traits (Chapter 3 of NRC 2002) • Reproductive system (tend to be: self-compatible & monoecious w/ asexual reproduction) • Flowering & fruiting periods (tend to be: long) • Juvenile period (tend to be: short) • Seed production (tend to be: high) • Germination cues (tend to be: present) • Light requirements (tend to be: highly efficient, plastic, & competitive)
What makes a species invasive? SUMMARY: Is it characteristics of the species?
What makes a species invasive? X SUMMARY: Is it characteristics of the species?
What makes a species invasive? X SUMMARY: Is it characteristics of the species? If not simply a characteristic of the species, then is it a characteristic of the environment?
What makes a species invasive? X SUMMARY: Is it characteristics of the species? If not simply a characteristic of the species, then is it a characteristic of the environment? Or both species and environment?
What makes a species invasive? X • SUMMARY: Is it characteristics of the species? • If not simply a characteristic of the species, then is it a characteristic of the environment? • Or both species and environment? • 10 hypothesis: (order subject to change) • Vacant niche hypothesis • Environmental change hypothesis • Microevolutionary change hypothesis • Escape from biotic constraints hypothesis • BCW hypothesis • Variable resource availability hypothesis • Competition hypothesis • Biodiversity hypothesis • Disturbance and land use hypothesis • Anthropogenic hypothesis
What makes a species invasive? • a) Vacant Niche Hypothesis “Niche” concept first developed by Grannell in 1917. Found that could differentiate species of thrushes on the basis of a resource (in his case, microhabitats)
What makes a species invasive? • a) Vacant Niche Hypothesis • Fundamental niche formalized by Hutchinson in 1957. • = theoretical limits of existence for a species along n resource axes
What makes a species invasive? • a) Vacant Niche Hypothesis • Fundamental niche formalized by Hutchinson in 1957. • = theoretical limits of existence for a species along n resource axes • Realized niche = actual limits of existence for a species
What makes a species invasive? • a) Vacant Niche Hypothesis Fundamental niche – Species A Success Resource axis #1
What makes a species invasive? • a) Vacant Niche Hypothesis Fundamental niche – Species A Success Success Resource axis #1 Resource axis #2
What makes a species invasive? • a) Vacant Niche Hypothesis Fundamental niche – Species A Resource axis #2 Resource axis #1
What makes a species invasive? • a) Vacant Niche Hypothesis Fundamental niche – Species A Resource axis #2 Resource axis #1
What makes a species invasive? • a) Vacant Niche Hypothesis Fundamental niche – Species A, Species B Resource axis #2 Resource axis #1
What makes a species invasive? • a) Vacant Niche Hypothesis Fundamental niche – Species A, Species B Resource axis #2 Resource axis #1
What makes a species invasive? • a) Vacant Niche Hypothesis Fundamental niche – Species A, Species B Resource axis #2 Resource axis #1
What makes a species invasive? • a) Vacant Niche Hypothesis Realized niche – Species A, Species B Resource axis #2 Resource axis #1
What makes a species invasive? • a) Vacant Niche Hypothesis Realized niche – Species A, Species B Fundamental niche: Invader – Species C Resource axis #2 Resource axis #1
Realized niche – Species A, Species B Fundamental niche: Invader – Species C Resource axis #2 Resource axis #1 • What makes a species invasive? • a) Vacant Niche Hypothesis
What makes a species invasive? • a) Vacant Niche Hypothesis New realized niche – Species A, Species B Realized niche: Invader – Species C Resource axis #2 Resource axis #1
What makes a species invasive? • a) Vacant Niche Hypothesis Realized niche – Species A, Species B Realized niche: Invader – Species C Fundamental niche: Invader –Species D Resource axis #2 Resource axis #1
What makes a species invasive? • a) Vacant Niche Hypothesis Realized niche – Species A, Species B Realized niche: Invader – Species C Fundamental niche: Invader –Species D Resource axis #2 Resource axis #1
What makes a species invasive? • a) Vacant Niche Hypothesis New realized niche – Species A, Species B Realized niche: Invader – Species C Realized niche: Invader –Species D Resource axis #2 Resource axis #1
What makes a species invasive? • a) Vacant Niche Hypothesis • SUMMARY:Vacant niches • May have some utility for tropical oceanic islands • BUT • Actual demonstration of “vacant” niche is nearly impossible • Many potential invaders lack pollinators, symbionts, etc.