Convergent / Parallel Evolution within the genus Jaltomata
revised 18 Dec 2018
Link to Jaltomata homepage
The information on this page may be cited as a communication with
professor Thomas Mione, Central Connecticut State University, Biology Department, Copernicus Hall,
1615 Stanley Street, New Britain, CT 06050-4010 USA, and
Segundo Leiva G., Universidad Privada Antenor Orrego, Av. América Sur 3145, Casilla postal 1075, Trujillo, Peru

Above: Within the genus Jaltomata different lineages have evolved different structures that partition nectar into five troughs.

Above Left: Radial thickenings organize nectar into five troughs; each trough is located between two neighboring radial thickenings. Jaltomata herrerae.

Above Right: A corona organizes nectar into five troughs; each trough is between two neighboring stamens.

Why partition nectar into troughs? Partitioning nectar into troughs: 1) must reduce evaporation (see next paragraph), 2) must contribute positively to the intensity of the visual signal to pollinators given that the nectar is colored, and 3) may encourage floral visitors to move around within the flower to continue to remove nectar, increasing the chances of contact between the anthers/stigma and the visitor.

Partitioning nectar into troughs reduces evaporation by: a) decreasing the nectar's ratio of surface area to volume, and b) locating the nectar where air currents are slower relative to wind currents outside of the flower. Natural selection would favor mechanisms/structures that reduce evaporation because: water may be limited, and evaporation increases the nectar's sugar concentration which leads to higher nectar viscosity. Viscosity rises exponentially with sugar concentration (Willmer, 2011). High nectar viscosity would limit the range of floral visitors because animals with longer tongues cannot drink more concentrated nectars and a concentrated sugar solution becomes too viscous to rise up or be sucked up a long thin tube (Willmer, 2011, page 206).

Above Right: Prior to the naming of J. calliantha it was refered to as J."hummingbird" (Miller et al. 2011) because Segundo Leiva and I had seen hummingbirds visiting the flowers in Peru.

Successful colonization from the Andes to the Peruvian lomas, a coastal desert habitat that receives all of its moisture as fog, occurred more than once in this genus.

Left: Jaltomata truxillana
Right: J. aspera
Both of these species grow in the lomas, but in the phylogeny of Miller et al. 2011 these are in different subclades of the orange-fruited clade.

Left photo is by Segundo Leiva G., right photo was provided by Graciela Vilcapoma S. and Arturo Granda P.

under construction

The following suite of characteristics seems to have evolved more than once: Flowers solitary, corolla purple and relatively large, style decreasing gradually in diameter proximal to distal, the stigma punctiform (not capitate).

Left: J. andersonii, clade 3d in Miller et al. 2011).

Right: J. quipuscoae, see Footnote 1 below, on this page, clade 3c in Miller et al. 2011. Photo by Victor quipuscoa.

under construction

In the genus Jaltomata, green fruits have evolved more than once

Left: J. chihuahensis, units along bottom are mm, photo by Thomas Mione

Right: J. quipuscoae, photo by Victor quipuscoa.

These two species are not closely related within the genus, and are classified in two different sections of the genus: J. chihuahenisis in section Jaltomata, and J. quipuscoae in section Modillonia.

Link to the only Jaltomata species of the Galápagos, J. werffii
In the genus Jaltomata colonization of oceanic islands has occurred more than once.

Link to the only Jaltomata species of the Greater Antilles, J. antillana
Link to J. procumbens race 321,
in section Jaltomata
In the genus Jaltomata, connivent stamens (connivent anthers) seem to have evolved more than once.
Link to J. paneroi,
in section Hebecladus.


Footnote 1. J. quipuscoa was not not included in Miller et al. 2011, but if included would be in the J. aspera, J. calliantha (J. "hummingbird") clade: only these three species have a corona.