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Full-Text Articles in Life Sciences
Observations On Why Mongrels May Make Effective Livestock Protecting Dogs, R. P. Coppinger, C. K. Smith, L. Miller
Observations On Why Mongrels May Make Effective Livestock Protecting Dogs, R. P. Coppinger, C. K. Smith, L. Miller
Charles Kay Smith
In Canid ontogeny from puppies to adults there is a very young phase before any species-specific predatory behavior has been expressed. This phase has been ontogenetically selected as a breed of neotenic adults which are ideal for protecting sheep. At a more advanced phase of canid ontogeny older puppies have begun to express separate pieces of species-specific predatory behavior, such as eye, stalk and chase but not the complete adult sequence so that crush bite kill and consume is as yet unexpressed. This intermediate phase was also ontogenetically selected as a breed such as border collies used in Britain to …
Behavior And Ecological Interactions Of Larval Odonata, Clay L. Pierce, Philip H. Crowley, Dan M. Johnson
Behavior And Ecological Interactions Of Larval Odonata, Clay L. Pierce, Philip H. Crowley, Dan M. Johnson
Clay L. Pierce
Enallagma aspersum and E. traviatum (Odonata: Coenagrionidae) are the most abundant larval odonates in Bays Mountain Park (Sullivan County, Tennessee, USA), although their spatial distributions are essentially nonoverlapping. E. traviatum coexists with insectivorous fish in a small lake, whereas E. aspersum is restricted to a small fishless pond nearby. Behavioral observations revealed that E. aspersum larvae were more active than E. traviatum, and tended to occupy more conspicuous positions. E. aspersum also engaged in more confrontations than E. traviatum, especially at higher density. In laboratorye xperimentsw ith juvenile bluegills( Lepomism acrochirusa) s predators,E . aspersum larvae were more vulnerable to …
Unidirectional Reproductive Incompatibility Between Aedes (Protomacleaya) Brelandi And A. (P.) Hendersoni (Diptera: Culicidae)., David B. Taylor, George B. Craig
Unidirectional Reproductive Incompatibility Between Aedes (Protomacleaya) Brelandi And A. (P.) Hendersoni (Diptera: Culicidae)., David B. Taylor, George B. Craig
David B Taylor
Forced mating was used to determine reproductive compatibility between two species in the Triseriatus Group of Aedes (Protomacleaya). In the cross between A. hendersoni Cockerell females and A. brelandi Zavortink males, only 7% of the females laid eggs that developed embryos. Furthermore, <5% of the eggs from single-female clutches in which one or more eggs did embryonate were fertile. In the reciprocal cross, A. brelandi females crossed to A. hendersoni males, 70% of the females laid fertile eggs and >80% of the eggs from those females became embryonated. Approximately 80% of the females were inseminated in both of the reciprocal crosses, No chromosomal abnormalities were observed in the hybrids. Incompatibility between the A. brelandi male genome and the A. hendersoni female cytoplasm appeared to be the cause of the reduced fertility.
Evolution At A Crossroads: The New Biology And The New Philosophy Of Science, David Depew, Bruce Weber
Evolution At A Crossroads: The New Biology And The New Philosophy Of Science, David Depew, Bruce Weber
David J Depew
No abstract provided.