Evolutionary Ecology

, Volume 4, Issue 3, pp 185–219

The evolution of bird-dispersed pines

  • Diana F. Tomback
  • Yan B. Linhart

DOI: 10.1007/BF02214330

Cite this article as:
Tomback, D.F. & Linhart, Y.B. Evol Ecol (1990) 4: 185. doi:10.1007/BF02214330


Twenty of approximately 100 species of pines (Pinus spp.) have wingless seeds, and 19 of these are in the subgenusStrobus. Eight of the wingless-seedStrobus pines are known to be dispersed by seed-storing corvids, particularly the nutcrackers (Nucifraga spp.), and the other 11 are presumed to be. The principal consequences of these nearly obligate bird-pine mutualisms include tree clustering and a population structure that differs from that of wind-dispersed pines. The wingless-seedStrobus pines in general are typified by ranges that include xeric conditions and/or high elevations, and large seeds, which are considered to be adaptive under either xeric or competitive conditions. The proposed evolutionary scenario for bird dependency begins with the distribution of ancestralStrobus pines into high elevation or semi-desert environments, sympatric with one or more seed-storing corvid forms, and an increase in seed size. We propose that dependency on birds for seed dispersal has occurred primarily in subgenusStrobus, becauseStrobus pines tend more towards winglessness and increased seed size in stressful environments than doPinus pines. Seed winglessness and other bird-pine traits probably arose from a combination of genetic drift in small populations and selection by corvids.


PinesPinusPinaceaesubgenusStrobussubgenusPinussubsectionCembraesubsectionCembroidessubsectionGerardianaesubsectionStrobiPinus cembraPinus albicaulisPinus flexilisPinus edulisPinus monophyllaCorvidaenutcrackersjaysNucifraga columbianaNucifraga caryocatactesseed cachingseed dispersalmutualismcoevolutionwinged seedwingless seedwind-dispersedbird-dispersedtree clustersbiogeographydirectional selectionreciprocal selectiongenetic driftinbreedingsmall populations

Copyright information

© Chapman and Hall Ltd. 1990

Authors and Affiliations

  • Diana F. Tomback
    • 1
  • Yan B. Linhart
    • 2
  1. 1.Department of BiologyUniversity of Colorado at DenverDenverUSA
  2. 2.Department of Environmental, Population, and Organismic BiologyUniversity of Colorado at BoulderBoulderUSA