Symposium: The Morphological Diversity of Intromittent Organs

The basic function of an intromittent organ seems deceptively simple – it mechanically introduces sperm into a female reproductive tract, thereby increasing a male’s probability of fertilization. But male copulatory structures seem to belie this simple function: they are extravagantly diverse and species-specific in form, examples include the long, coiled phalluses of waterfowl; the complex beetle aedeagus; the spiked, smooth, and curlicued penises of mammals; the long rod-like gonopodia of poecilid fish; and paired snake hemipenes, to name a few. Although biologists historically addressed morphological differences among intromittent organs in light of their value as taxonomic characters, more recent studies have begun to examine the selective mechanisms that produce their diverse forms.

Many selective pressures affect intromittent organ anatomy. As copulatory structures they are on the front line of male reproductive strategies, and their functional anatomy is probably under strong natural selection, although some studies have uncovered deep molecular homologies and shared genetic programs that may developmentally limit their diversity of shape. But intromittent organs do not work in isolation: because they interact directly with female structures, their form can also be affected by female reproductive strategies such as cryptic female choice, or by strategies that lead to sexual conflict.

The goal of this symposium is to create a synthetic understanding of the factors that make intromittent organs some of the most morphologically diverse structures in the animal kingdom. We are bringing together scientists who share the common goal of understanding the development, function, and evolution of intromittent organs in the context of reproductive behavior. Speakers will address the varied influences on the evolution of intromittent organs in both vertebrates and invertebrates, including ecological interactions, competing selective pressures, phenotypic plasticity, sexual conflict, life history, genes and development, and the biomechanics of copulation. Speakers will further address some of the potentially far-reaching consequences of genital evolution on reproductive isolation, i.e. speciation. By combining morphological, developmental, and behavioral researchers in one symposium we hope to foster a forward-looking and holistic understanding of the genesis and operation of intromittent organs.

Sponsors: DVM, DCB, DCE, DIZ, and AMS
  
This symposium also received funding from Sewanee: The University of the South

Organizers

• Brandon C. Moore (Sewanee: The University of the South)
• Diane A. Kelly (University of Massachusetts Amherst)

Speakers

S5.1 Tuesday, Jan. 5, 08:00 KELLY, Diane A.:

Intromittent Organ Morphology and Biomechanics: Exploring the Morphospace of Intromission

S5.2 Tuesday, Jan. 5, 08:30 BURNS, M.*; TSURUSAKI, N.:

Reproductive morphology under long-term demographic evolution in an arthropod

S5.3 Tuesday, Jan. 5, 09:00 HOCH, JM*; SCHNECK, DT; NEUFELD, CJ:

Ecology and evolution of phenotypic plasticity in the penis and appendages of barnacles

S5.4 Tuesday, Jan. 5, 09:30 LANGERHANS, R. Brian*; ANDERSON, Chris M.; HEINEN-KAY, Justa L.:

Causes and consequences of genital diversity: ecology and speciation as the missing links

S5.5 Tuesday, Jan. 5, 10:30 COHN, MJ:

Development of external genitalia: from evolutionary origins to congenital malformations

S5.6 Tuesday, Jan. 5, 11:00 TUNSTALL, P; RAPKIN, J; GAGE, M; HUNT, J; HOUSE, C.M*:

A ROLE FOR STABILIZING SEXUAL SELECTION FOR THE EVOLUTION OF MALE AND FEMALE GENITALIA IN A FLOUR BEETLE (Tribolium castaneum)

S5.7 Tuesday, Jan. 5, 11:30 GREDLER, M.L.:

Developmental and Evolutionary Origins of Amniote External Genitalia

S5.8 Tuesday, Jan. 5, 13:30 BRENNAN, PLR:

THE ROLE OF GENITAL COEVOLUTION IN INTROMITTENT ORGAN MORPHOLOGY. The Role of Genital Coevolution in Intromittent Organ Morphology

S5.9 Tuesday, Jan. 5, 14:00 SCHULTZ, N.; INGELS, J.; HILLHOUSE, A.; WARDWELL, K.; CHANG, P.; GOOD, J.M.; CHEVERUD, J.; WILLIAMS, R.; LU, L.; WILLIAMS, R.; DEAN, M.D.*:

Evolutionary genetics of baculum size and shape variation in mice

S5.10 Tuesday, Jan. 5, 14:30 ORR, T.J.*; BRENNAN, P.L.R.:

All features great and small – an exploration of male genital evolution in mammals

S5.11 Tuesday, Jan. 5, 15:00 MOORE, BC*; SPEARS, D; KELLY, DA:

Morphological characteristics related to the expansion of the crocodilian glans for reproductive activity.