Post on 03-Jan-2016
Invasion of the Black RatInvasion of the Black RatRattus rattusRattus rattus
Alexis RoqueAlexis Roque
Karin Lisa SirjooKarin Lisa Sirjoo
Rattus rattusRattus rattus Overview Overview
The black rat is invasive and found in The black rat is invasive and found in tropical coastal regionstropical coastal regions
Displace native species in all areasDisplace native species in all areas Vector for spread of various diseases to Vector for spread of various diseases to
endemic speciesendemic species
Research StudiesResearch Studies
Study 1: Potential spread of introduced black rat Study 1: Potential spread of introduced black rat ( Rattus rattus ) parasites to endemic deer mice ( Rattus rattus ) parasites to endemic deer mice ( Peromyscus maniculatus ) on the California ( Peromyscus maniculatus ) on the California Channel Islands. (Smith, Katherine F., Channel Islands. (Smith, Katherine F., Carpenter, S.M. 2006.) Carpenter, S.M. 2006.)
Study 2: Space invaders? A search for patterns Study 2: Space invaders? A search for patterns underlying the coexistence of alien black rats underlying the coexistence of alien black rats and Galapagos rice rats. (Harris, Donna B., and Galapagos rice rats. (Harris, Donna B., Gregory, S.D., Macdonald, D.W. 2006.)Gregory, S.D., Macdonald, D.W. 2006.)
Deer Mice Deer Mice Deer Mice are the only Deer Mice are the only
native mammals found on native mammals found on the California Channel the California Channel IslandsIslands
Isolated from main land Isolated from main land and have unique and have unique subspeciessubspecies
Black rat is invasive to Black rat is invasive to islands and have islands and have introduced new parasitesintroduced new parasites
Lasting effects on island Lasting effects on island populationspopulations
http://www.sdnhm.org/fieldguide/mammals/images/deermouse-250.jpg
MethodsMethods
Donation of specimens - Black rat & Deer Donation of specimens - Black rat & Deer Mice Mice
Collected from six of the eight islands Collected from six of the eight islands Small mammal live trapping practices Small mammal live trapping practices Euthanized, frozen, transported Euthanized, frozen, transported Sexed, aged, weighed Sexed, aged, weighed Dissected and sampled for parasitesDissected and sampled for parasites
Parasites processed by type Parasites processed by type
Collection SitesCollection Sites
Figure 1. California Channel Islands where individuals were collected Figure 1. California Channel Islands where individuals were collected
Parasite AnalysisParasite Analysis Inter-specific parasite transfer criteria:Inter-specific parasite transfer criteria:
1.1. Infects both species on islands where both Infects both species on islands where both co-exist co-exist
2.2. Does not infect deer mouse on islands Does not infect deer mouse on islands where black rat is absentwhere black rat is absent
3.3. Infects black rats in other regions Infects black rats in other regions
http://www.nematode.net/IMAGES/worms2%5b1%5d.jpg
Trichuris murisTrichuris muris
http://www.umanitoba.ca/science/zoology/faculty/dick/z346/images/syphacia3.jpg
SyphaciaSyphacia
http://www.4optimallife.com/Images/tapeworm.jpg
Hymenolepis Hymenolepis
ResultsResults
Protospirura Protospirura peromysci peromysci & & Trichus Trichus muris muris
Trichus muris Trichus muris met the met the inter-specific parasite inter-specific parasite transfer criteriatransfer criteria
Results show that Results show that T. T. murismuris spread from spread from black rat to deer miceblack rat to deer mice
Trichus muris Trichus muris prevailed in deer mice prevailed in deer mice where black rat was where black rat was removedremoved
http://wotan.cse.sc.edu/perobase/images/p_manicu.jpg
Study No. 1 ConclusionStudy No. 1 Conclusion
Overlapping habitats and similar foraging Overlapping habitats and similar foraging behaviors = parasite transfer behaviors = parasite transfer
Frequency of Frequency of T. murisT. muris depends on host depends on host density density
Results provide conservation implications:Results provide conservation implications: Parasites found in introduced species should Parasites found in introduced species should
not be ignorednot be ignored Parasites can remain in a population even Parasites can remain in a population even
after founder host is removedafter founder host is removed
Black rats and Galápagos rice rats
Galapagos islands West of Ecuador in
the Pacific Ocean Nesoryzomys swarthi
presumed extinct in 1906
Black rat introduced in the late 1600s
N. swarthi rediscovered in 1997
Fig. 1 Map of Santiago showing hair tube survey sites.
Black rats and Galápagos rice rats
SIMILARITIES Omnivorous – eats
fruits, seeds, invertebrates
DIFFERENCES Black rat is larger;
more aggressive Nocturnal Peak activity 2-3
hours after darkness
How do they coexist?
Black rats and Galápagos rice rats
METHODS Baited hair tubes Sites along the north coast, inland, and
highland Hairs extracted Species identified
Black rats and Galápagos rice rats
RESULTS 10 sites inhabited by
N. swarthi Mostly thorn scrub
habitat R. rattus present at all
sites
Fig. 2 Opuntia and Bursera thorn scrub habitat at La Bomba
Black rats and Galápagos rice rats
Fig. 3 Abundance of N. swarthi and R. rattus from live trappingon four coastal (1–4) and four inland (5–8) grids at thestart of the 2003 wet season (December 2002–January 2003)
Black rats and Galápagos rice rats
RESULTS Significant correlation with presence of
mature cacti and rice rats Rice rats found mainly in coastal regions
Black rats and Galápagos rice rats
CONCLUSION Populations of rice rats closely correlated with
Opuntia cactus density Black rats do not or can not consume cactus
fruits Cactus provide a crucial resource refuge for
rice rats allowing for coexistence with the black rat
Further Recommendations
Propose a study where cactus are used as main vegetation.
Follow the interactions and population numbers of rice rats versus black rats
Introduce parasite to black rats Use arid conditions which black rats prefer
as control environment Compare rates of parasite transfer in 2
environments
References References
Smith, Katherine F., Carpenter, S.M. 2006. Potential spread of Smith, Katherine F., Carpenter, S.M. 2006. Potential spread of introduced black rat (introduced black rat (Rattus rattusRattus rattus) parasites to endemic deer ) parasites to endemic deer mice (mice (PeromyscusPeromyscus maniculatusmaniculatus) on the California Channel ) on the California Channel Islands. Diversity distributions Islands. Diversity distributions 1212:742.:742.
Harris, Donna B., Gregory, S.D., Macdonald, D.W. 2006. Harris, Donna B., Gregory, S.D., Macdonald, D.W. 2006. Space invaders? A search for patterns underlying the Space invaders? A search for patterns underlying the coexistence of alien black rats and Galapagos rice rats. coexistence of alien black rats and Galapagos rice rats. Oecologia Oecologia 149149:276-288.:276-288.