Does the morphological fit between flowers and pollinators affect pollen deposition? An experimental test in a buzz‐pollinated species with anther dimorphism

Some pollination systems, such as buzz‐pollination, are associated with floral morphologies that require a close physical interaction between floral sexual organs and insect visitors. In these systems, a pollinator's size relative to the flower may be an important feature determining whether the visitor touches both male and female sexual organs and thus transfers pollen between plants efficiently. To date, few studies have addressed whether in fact the “fit” between flower and pollinator influences pollen transfer, particularly among buzz‐pollinated species. Here we use Solanum rostratum, a buzz‐pollinated plant with dimorphic anthers and mirror‐image flowers, to investigate whether the morphological fit between the pollinator's body and floral morphology influences pollen deposition. We hypothesized that when the size of the pollinator matches the separation between the sexual organs in a flower, more pollen should be transferred to the stigma than when the visitor is either too small or too big relative to the flower. To test this hypothesis, we exposed flowers of S. rostratum with varying levels of separation between sexual organs, to bumblebees (Bombus terrestris) of different sizes. We recorded the number of visits received, pollen deposition, and fruit and seed production. We found higher pollen deposition when bees were the same size or bigger than the separation between anther and stigma within a flower. We found a similar, but not statistically significant pattern for fruit set. In contrast, seed set was more likely to occur when the size of the flower exceeded the size of the bee, suggesting that other postpollination processes may be important in translating pollen receipt to seed set. Our results suggest that the fit between flower and pollinator significantly influences pollen deposition in this buzz‐pollinated species. We speculate that in buzz‐pollinated species where floral morphology and pollinators interact closely, variation in the visitor's size may determine whether it acts mainly as a pollinator or as a pollen thief (i.e., removing pollen rewards but contributing little to pollen deposition and fertilization).     

Los domacios de Mortoniodendron (Malvaceae s.l.)

We describe the domatia of nine species of the genus Mortoniodendron, based on observations of cleared leaves and scanning electron micrographs. We recognize four kinds of domatia in Mortoniodendron species: cryptpocket, crypt, pocket and tufts of hairs, mostly associated with primary, secondary and tertiary veins. Mortoniodendron anisophyllum and M. costaricense have domatia up to the tertiary and quaternary veins. Moreover, domatia are absent in only two species, M. pentagonum and M. uxpanapense. Although there are reports on the occurrence of domatia in Malvaceae s.l., mainly in Brownlowioideae, Sterculioideae, and Tilioideae subfamilies, they are poorly described, and based on the different types of domatia found in Mortoniodendron we suggest reviewing other genera to better describe the diversity of domatia in Malvaceae s.l.

---

Resumen  Se describen los domacios presentes en nueve especies del género Mortoniodendron utilizando la técnica de diafanización y el microscopio electrónico de barrido. En el género se observaron cuatro tipos de domacios: criptabolsa, cripta, bolsa y mechón de tricomas, la mayoría asociados a las venas primaria, secundarias y terciarias. Mortoniodendron anisophyllum y M. costaricense tienen domacios hasta las bifurcaciones de venas terciarias y cuaternarias. únicamente en dos especies, M. pentagonum y M. uxpanapense, los domacios están ausentes. A pesar de que se han registrado domacios en miembros de Malvaceae s.l., predominantemente en las subfamilias Brownlowioideae, Sterculioideae y Tilioideae; pocas veces se describe su tipo. Por ello, con base en los diferentes tipos de domacios encontrados en Mortoniodendron sugerimos estudiar otros géneros y confirmar la diversidad en Malvaceae s.l.

     

Population Structure and Genetic Diversity of Native and Invasive Populations of Solanum rostratum (Solanaceae)

Aims

We investigate native and introduced populations of Solanum rostratum, an annual, self-compatible plant that has been introduced around the globe. This study is the first to compare the genetic diversity of Solanum rostratum between native and introduced populations. We aim to (1) determine the level of genetic diversity across the studied regions; (2) explore the likely origins of invasive populations in China; and (3) investigate whether there is the evidence of multiple introductions into China.

Methods

We genotyped 329 individuals at 10 microsatellite loci to determine the levels of genetic diversity and to investigate population structure of native and introduced populations of S. rostratum. We studied five populations in each of three regions across two continents: Mexico, the U.S.A. and China.

Important Findings

We found the highest genetic diversity among Mexican populations of S. rostratum. Genetic diversity was significantly lower in Chinese and U.S.A. populations, but we found no regional difference in inbreeding coefficients (F _IS) or population differentiation (F _ST). Population structure analyses indicate that Chinese and U.S.A. populations are more closely related to each other than to sampled Mexican populations, revealing that introduced populations in China share an origin with the sampled U.S.A. populations. The distinctiveness between some introduced populations indicates multiple introductions of S. rostratum into China.     

Tomato variety affects larval survival but not female preference of the generalist moth Trichoplusia ni

In herbivorous insects, the choice that females make for a suitable host plant is crucial for survival of its offspring because the neonate larvae are generally not capable of moving great distances. The preference-performance hypothesis states that herbivore females will choose to oviposit on hosts on which their offspring will have better performance. In this study, we investigated whether Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae) females are able to discriminate among a weedy race, a landrace, and a commercial cultivar of tomato plants, Solanum lycopersicum L. (Solanaceae), and how their choice affects the offspring performance. Additionally, we identified the volatile compounds and recorded the density of glandular trichomes of the tomato plants. Females did not show a preference for any of the three types of tomato plants. Females oviposited more on the adaxial surface of leaves of commercial cultivar plants than on (any surface of) leaves of weedy-race plants. The relative abundance of volatiles varied quantitatively among the three types of tomato plants. Commercial cultivar plants released a higher abundance of volatiles than weedy race and landrace plants. Weedy-race plants had a higher density of glandular trichomes types I and VI than the commercial cultivar. More neonate larvae died if fed on the weedy race and landrace plants than when reared on commercial cultivar plants. Results suggested that the higher mortality of T. ni larvae may be related to a higher density of glandular trichomes on landrace and weedy-race plants than on commercial cultivar plants, although other constitutive and induced defenses may be involved. Our results do not support the preference-performance hypothesis.     

Leaf architecture and anatomy of eleven species of Mortoniodendron (Malvaceae s.l.)

The genus Mortoniodendron is distributed from southeastern Mexico to Colombia and contains about 18 species of trees and shrubs. The main goal of this study is to describe and compare the leaf architecture and the anatomy of 11 species of Mortoniodendron using cleared leaves and paradermal and transverse leaf sections. All of the species of Mortoniodendron share a simple lamina with an entire margin. The differences among the species include the venation pattern, the relative thickness and course of the secondary veins, the presence or absence of the intersecondary veins, the tertiary vein pattern, the number of branches in veinlets, and the marginal ultimate venation. The leaf anatomy is similar to other species of the Malvaceae s.l.: for example, mucilage cells are common in Mortoniodendron. There are unique attributes of the leaf architecture and anatomy, such as the eucamptodromous venation pattern of M. guatemalense, which facilitates the identification of the species. The species M. palaciosii, M. pentagonum, M. ruizii, M. uxpanapense, and M. sp. nov. share features that suggest that they are closely related.