Abstract Detail

Questioning Species and Species Complexes: A Colloquium in Honor of Dr. R. James Hickey

Klein, Laura [1], Miller, Allison [2], Hickey, R. [3].

Evolutionary insights from morphology: lessons from two plant lineages.

Morphological variation in plants can indicate genetic and environmental interaction. Through the study of morphology, we can apply meaningful context to genetic regulation and development as well as glean insights into mechanisms of variation, such as recombination through intra- or interspecific gene flow. Gene flow can provide a mechanism for natural selection to drive larger ecological and evolutionary processes such as local adaptation through natural selection, speciation, or ecological divergence. However, the extent to which gene flow occurs and its evolutionary outcomes are understudied. Here, two studies from different plant lineages that characterize morphological variation in multiple species demonstrate that the presence of gene flow may occur in the presence of species maintenance. First, North American Diphasiastrum complanatum, D. digitatum, and D. tristachyum (Lycopodiaceae) exhibit evidence of interspecific gene flow in which F1 offspring have the ability to interbreed with each other and with parental taxa, forming introgressive offspring that are morphologically intermediate between the original parental forms. To test for introgression, morphological measurements for parental and putative hybrid taxa were collected and analyzed using principle components analyses and hybrid indices. Results support the presence of introgression among all three pair combinations. Although not infrequent, the numbers of hybrid forms are far exceeded by parental forms and so there are no compelling reasons not to recognize these three taxa at the species level. In Vitaceae, economically important and ecologically pervasive North American Vitis species offer a unique opportunity to examine similar evolutionary patterns. Interspecific hybridization is widely used in viticulture to produce more vigorous plants and is well documented in nature; however, the extent of gene flow among North American Vitis congeners within natural populations remains underexplored. Vitis leaves are frequently used in evolutionary studies and cultivation practices, which make excellent characters for describing patterns of variation. Leaf morphological variation within and among Vitis species growing in a latitudinal transect were described, revealing a continuum of distinct leaf shapes within these levels of biological organization. Interestingly, there was preliminary observational evidence that V. rupestris leaf morphology exhibits a narrower range of variation when growing in sympatry with V. vulpina than when it occurs in allopatry. This pattern may be indicative of ecological competition occurring between these two Vitis species. In both studies, morphological variation offers important insights into the complex evolutionary trajectories of these species.

1 - Saint Louis University, Biology Department, 3507 Laclede Ave, Saint Louis, MO, 63103, United States
2 - Saint Louis Univ./Danforth Plant Science Center, Biology, 3507 Laclede Avenue, Macelwane Hall, St. Louis, MO, 63110, United States
3 - Miami University, Botany, Pearson Hall, room 316, Oxford, OH, 45056, United States

Keywords:
morphology
morphometrics
hybridization
introgression
Lycopodiaceae
Vitaceae.

Presentation Type: Colloquium Presentations
Session: CO12, Questioning Species and Species Complexes: A Colloquium in Honor of Dr. R. James Hickey
Location: San Luis 1/Starr Pass
Date: Wednesday, July 31st, 2019
Time: 3:45 PM
Number: CO12009
Abstract ID:1023
Candidate for Awards:None