Ecology and Conservation of Invertebrates • Unique aspects of the ecology of invertebrates • Issues in the conservation of invertebrates Invertebrate Ecology • Predominance of complex lifecycles where juvenile forms differ morphologically and ecologically from adult forms • Presence of eruptive dynamics • Role in decomposition • Role as parasites Consequences of complex life cycles in Invertebrates • Processes affecting dynamics of juveniles may differ and be unrelated to those affecting dynamics of adult populations • Juveniles and adult do not compete for the same food resources • Juvenile and adult forms may be specialized for a limited set of functions, such a feeding, dispersal, and/or reproduction • Most species tend to be highly fecund, but juvenile survival rates are low Eruptive Dynamics
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Ecology and Conservation of Invertebrate Ecology Invertebrates
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Ecology and Conservation of Invertebrates
• Unique aspects of the ecology of invertebrates
• Issues in the conservation of invertebrates
Invertebrate Ecology
• Predominance of complex lifecycles where juvenile forms differ morphologically and ecologically from adult forms
• Presence of eruptive dynamics• Role in decomposition• Role as parasites
Consequences of complex life cycles in Invertebrates
• Processes affecting dynamics of juveniles may differ and be unrelated to those affecting dynamics of adult populations
• Juveniles and adult do not compete for the same food resources
• Juvenile and adult forms may be specialized for a limited set of functions, such a feeding, dispersal, and/or reproduction
• Most species tend to be highly fecund, but juvenile survival rates are low
Eruptive Dynamics
African Plague Locust –Schisotcerca gregaria
Locust Plagues(Insecta: Orthoptera)
March 2004 Cameraria hamdryadella
Dynamics of Cameraria hamadryadella(Lepidoptera: Gracillariidae)
• The decomposition of dead plant, animal tissues, and fecal matter is accelerated by the activity of invertebrates
• By physically assisting in the break-up of plant and animal tissues, increasing surface area for bacterial and fungal activity
• By ingestion and digestion of plant and animal tissues or feces
• Widespread in marine, freshwater, and terrestrial environments involving members of most phyla
Why Conserve Invertebrates?
• Speciesist arguments that they have a right to existence
• Aesthetically pleasing• Legally mandated• Provide valuable Ecosystem Services• Are a resource for human use (food,
biochemicals, jewelery, etc.)
Right to Existence
• Some ethicists argue that not only individuals, but also species have a right to existence
• Other ethicists claim that all rights are vested in individuals, not in larger aggregate entities like species or other taxonomic categories
Aesthetically Pleasing
• Most humans find butterflies and some other invertebrates aesthetically pleasing (scarab beetles, corals, anything else?)
• However, most invertebrate groups do not have the charismatic appeal of birds and mammals
• Most humans see invertebrates more as vermin and as threats than as attractive and worthy of conservation efforts
Legally Mandated
• Endangered Species Act or USA and California
• International Prohibitions on Trade and Transport
Ecosystem Services
Ecosystem services are the essential functions of ecosystems that are carried out via the activities of plant or animal groups.
For example, plants function as primary producers fixing carbon and energy using CO2 and sunlight.
Ecosystem Services provided by Invertebrates
• Pollination• Seed dispersal• Natural enemies of other pests• Decomposition• Soil formation
Invertebrates as a Resource
• Source of food for humans• Bait for fishing• Sponges for bathing • Corals, Conchs, Oysters and others for jewelry• Cloth production (silk)• Bees as pollinators of crops• Wasps, beetles, mantids, spiders, for biocontrol• Medicinal use of leeches• Target of bio-prospecting
• Formerly abundant European Crayfish• Pollution (DDT and lake acidification) • Fungal disease introduced from North
America• Competition with introduced crayfish• Size based catch limitation and attempts to
stop disease spread
Extinct Insects in the Bay Area
• First recorded extinction of a native US insect Satyr butterfly (Cercyonis sthenelesthenele (19th century)
• Pheres Blue butterfly (Icaricia icaroidespheres) and Xerces blue (Glaucopsychexerces) extinct in 20th century
• Antioch dune shield back katydid (Nedubaextincta), extinct before it was described from a single museum specimen
Endangered Insects in the Bay Area
Elaphrus viridisDelta green beetleColeoptera
Euphydryas editha bayensisBay checkerspot
Speyeria zene myrtleaeMyrtle’s silverspot
Speyeria callippe callippeCallippe silverspot
Icaricia incaroides missionensisMission blue
Speyeria zene behrensiiBehren’s silverspot
Incisalia mossii bayensisSan Bruno elfin
Apodemia mormo langeiLange’s metalmarkLepidoptera
Insect Conservation in the Bay Area
• Hard to know what species were here before extensive human settlement
• Of the pinned insect collection in the CAS, 248,565 specimens represent 8,668 species and sub-species
• West Germany has 9,694 species and is 13.9 times larger than the 9 county region
• CAS estimate an underestimate• Recent sampling of bees in Napa and Sonoma counties
recorded 17 and 10 species respectively, that are not in the CAS collection
San Francisco butterflies and insects
• 46 species of butterflies native to San Francisco• Only 26 species have been observed in the last 15 years• 3 species are known to be extinct, but the other species
occur in other counties• Given that only 14% of the land area of San Francisco is in
parks, we would predict using the species-area relationship that 18 species should have been lost from San Francisco, but about 20 have been
• So about 6.5% of the insects native to San Francisco are possibly extinct and 43% are no longer found in there , but persist in adjacent counties
Introduced Species - Snails
• Giant African snail Achatina fulica – dispersed by people for food, but became a crop pest
• Euglandina rosea was introduced on various Pacific islands to control Achatina
• Euglandina has caused the extinction of native snails on Morrea in the genus Partula, and has been sown to prey on aquatic species as well
Giant African Snail Euglandina rosea
Introduced Invertebrates in California
• 177 species of insects invaded California between 1955 and 1988 (5 species/year)
• Over 200 species of invertebrates have invaded San Francisco Bay and in some areas of the Bay account for 95% of the biomass
Summary
• Ecology of invertebrates highly diverse• Growing number of invertebrate species are
endangered or threatened by human activities
• Invertebrates are valuable resources for humans, but our ignorance of their biology and distribution hamper conservation