The  EVOLUTION  of  MORALITY IMAGE 10A   
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Concept/Content "Selfish" cooperation / Florida scrub jay parents with helper sibling on nest
Information caption Three Florida scrub jays at their nest. Mother (10 yrs old) and daughter (7 yrs. old) are on the nest. Father (3 yrs. old) perches above. Nestling is 18 days old.
When Florida scrub jays (Aphelocoma coerulescens) reach reproductive age, they do not always "leave home" and begin their own families. Rather, they help raise their younger siblings: an apparent cost when compared with their own reproductive potential. But the context of reproduction is complex. Outcomes change with a broader perspective. A male scrub jay must have his own territory for foraging and nesting, and territory is limited. Males who stay with their father can help gradually expand the father's territory, which is eventually split between father and son. This way the son is better able to secure good territory. Females, by contrast, compete for males with the best territories. A female who can wait for opportunity is able to select a better mate. In each case, the scrub jay actually benefits reproductively in the long-term by staying at home and helping their parents reproduce in the short-term (Woolfenden and Fitzpatrick 1978, 1984).
Inquiry caption Here's an interesting nest: The chick is 18 days old. The father perches above. But on the nest are both the mother and the chick's older sibling. The sibling is old enough to reproduce herself: why is she helping to raise her sibling, rather than having a nest of her own? (Can you propose any hypotheses?)
When Florida scrub jays (Aphelocoma coerulescens) reach reproductive age, they do not always leave home and begin their own families. A male scrub jay must have his own territory for foraging and nesting, and territory is limited. Imagine a male who stays with his father. He can help gradually expand the father's territory. How might this benefit the son?" [Eventually, the territory can be split between father and son. This way the son is better able to secure good territory.]
"Females, by contrast, compete for males with the best territories. How might staying at home be beneficial?" [A female who can wait for opportunity is able to select a better mate.]
In each case, the scrub jay actually benefits reproductively in the long-term by staying at home and helping their parents reproduce in the short-term (Woolfenden and Fitzpatrick 1978, 1984). When viewed in a larger context, an apparent cost actually increases their own reproductive potential, and is favored by natural selection.
Reproductive helpers are also found in black-backed jackals (Canis mesomelas), cichlid fish of Lake Tanganyika (Lamprologus brichardi), grey-crowned babblers of Australia (Pomatostomus temporalis), carrion crows in northern Spain (Corvis corone corone) and many other species (Krebs and Davies 1993, pp.299-302; Clutton-Brock 2002; Baglione et al 2003).
Target Concept: Some cases of "costly" helping are apparent only.
Photographer J.W. Fitzpatrick and G.E. Woolfenden
Credit Courtesy of John W. Fitzpatrick, Cornell Lab of Ornithology & Archbold Biological Station
SIZE in pixels [file size] 650x479

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