scholarly journals Reversal of height dimorphism promotes pollen and seed dispersal in a wind-pollinated dioecious plant

2011 ◽  
Vol 8 (2) ◽  
pp. 245-248 ◽  
Author(s):  
Melinda Pickup ◽  
Spencer C. H. Barrett
Keyword(s):  
Life Cycle ◽  
Seed Dispersal ◽  
Field Survey ◽  
Adaptive Significance ◽  
Height Growth ◽  
Field Observations ◽  
Dioecious Plant ◽  
Seed Maturity ◽  
Pollen And Seed Dispersal ◽  
Rumex Hastatulus

Variation in the timing of reproductive functions in dioecious organisms may result in adaptive changes in the direction of sexual dimorphism during the breeding season. For plants in which both pollen and seeds are wind-dispersed, it may be advantageous for male plants to be taller when pollen is dispersed and female plants to be taller when seeds are dispersed. We examined the dynamics of height dimorphism in Rumex hastatulus , an annual, wind-pollinated, dioecious plant from the southern USA. A field survey of seven populations indicated that females were significantly taller than males at seed maturity. However, a glasshouse experiment revealed a more complex pattern of height growth during the life cycle. No dimorphism was evident prior to reproduction for six of seven populations, but at flowering, males were significantly taller than females in all populations. This pattern was reversed at reproductive maturity, consistent with field observations. Males flowered later than females and the degree of height dimorphism was greater in populations with a later onset of male flowering. We discuss the potential adaptive significance of temporal changes in height dimorphism for pollen and seed dispersal, and how this may be optimized for the contrasting reproductive functions of the sexes.

scholarly journals SELECTIVE INTERACTIONS BETWEEN SHORT-DISTANCE POLLEN AND SEED DISPERSAL IN SELF-COMPATIBLE SPECIES

Evolution ◽  
2006 ◽  
Vol 60 (11) ◽  
pp. 2257-2271 ◽  
Author(s):  
Virginie Ravigné ◽  
Isabelle Olivieri ◽  
Santiago González Martinez ◽  
François Rousset
Keyword(s):  
Seed Dispersal ◽  
Short Distance ◽  
Pollen And Seed Dispersal ◽  
Selective Interactions

The timing of conflict and cooperation among cofoundresses of the social wasp Polistes fuscatus (Hymenoptera: Vespidae)

1996 ◽  
Vol 74 (1) ◽  
pp. 70-74 ◽  
Author(s):  
George J. Gamboa ◽  
Katherine A. Stump
Keyword(s):  
Social Wasp ◽  
Adaptive Significance ◽  
Field Observations ◽  
Polistes Fuscatus ◽  
Conflict And Cooperation ◽  
Colony Cycle ◽  
The Social ◽  
Theoretical Predictions ◽  
Ecological Pressure ◽  
Temporal Overlap

Field observations were made on 37 preworker, multiple-foundress colonies of the social wasp Polistes fuscatus. In total, 401.9 h of behavioural observations of cofoundresses were conducted at three different periods prior to the emergence of workers. Cofoundresses displayed a marked, significant increase in aggression at about the time in the colony cycle when reproductive-destined eggs began to be laid. Both queens and their subordinates became increasingly aggressive at this time. These empirical results support theoretical predictions that conflict among cofoundresses would intensify over the production of reproductive-destined (but not worker-destined) eggs. Cooperation in foraging to minimize nest inattendance as well as synchronicity (temporal overlap) in activity also increased significantly at the onset of the production of reproductive-destined eggs. Thus, conflict and cooperation are not necessarily antagonistic in P. fuscatus. Foundresses minimized the time that nests are unattended at a time in the colony cycle when most conspecific usurpations occur. This suggests that the ecological pressure of conspecific usurpation has favoured increased coordination in foraging to minimize the time nests are unattended. The adaptive significance, if any, of an increase in synchronicity of activity among cofoundresses at the onset of the production of reproductives is not obvious.

scholarly journals Natural history of Ctenus medius Keyserling, 1891 (Araneae, Ctenidae) I: observations on habitats and the development of chromatic patterns

2000 ◽  
Vol 60 (3) ◽  
pp. 503-509 ◽  
Author(s):  
C. E. ALMEIDA ◽  
E. F. RAMOS ◽  
E. GOUVÊA ◽  
M. do CARMO-SILVA ◽  
J. COSTA
Keyword(s):  
Life Cycle ◽  
Natural History ◽  
National Park ◽  
Common Species ◽  
Field Observations ◽  
Mata Atlântica ◽  
Adult Females ◽  
History Of ◽  
Males And Females ◽  
Phoneutria Nigriventer

Ctenus medius Keyserling, 1891 is a common species in several spots of Mata Atlântica, however there is a great lack of studies in all aspects of its natural history. This work aims to elucidate aspects of ecotope preference compared to large spiders, and to provide data on the development of chromatic patterns during its life cycle. The observations on the behavior of C. medius were done in the campus of Centro Universitário de Barra Mansa (UBM) by means of observations and nocturnal collections using cap lamps. For observations on the development of chromatic patterns, spiderlings raised in laboratory, hatched from an oviposition of a female from campus of UBM, and others spiderlings collected in field were used. The field observations indicate that: C. medius seems to prefer ecotopes characterized by dense shrub vegetation or herbal undergrowth; Lycosa erythrognatha and L. nordeskioldii seems to prefer open sites; Phoneutria nigriventer seems to prefer shrub vegetation and anthropogenic ecotopes as rubbish hills; Ancylometes sp. seems to prefer ecotopes near streams. Concerning chromatic patterns, it was observed that males and females show well distinct patterns during the last two instars, allowing distinction by sex without the use of a microscope. Through chromatic patterns it was also possible to draw a distinction between C. medius and C. ornatus longer that 3 mm cephalothorax width. 69 specimens of C. medius (males and females) collected in the campus of UBM did not show a striking polymorphism in chromatic pattern, but one among 7 adult females collected in National Park of Itatiaia, showed a distinct chromatic pattern.

Application of Life Cycle Risk Assessment (LCRA) of Fish to Different Suburban Streams

2010 ◽  
Vol 5 (3) ◽  
Author(s):  
Yusuke Bando ◽  
Nobuhiko Kikuchi ◽  
Yutaka Sakakibara
Keyword(s):  
Risk Assessment ◽  
Life Cycle ◽  
Dissolved Oxygen ◽  
Human Activities ◽  
Field Survey ◽  
Freshwater Fishes ◽  
Habitat Conditions ◽  
Pollution Levels ◽  
Literature Reviews ◽  
Good Agreement

A Life Cycle Risk Assessment (LCRA) proposed in our former study was applied to 12 suburban streams to evaluate crucial stress and habitat conditions for 15 freshwater fishes in Japan. In LCRA, 8 stresses produced by human activities were taken into consideration, referring to the literature. Field survey and literature reviews were conducted to identify the present existence and distributions of corresponding fishes in the streams which have different pollution levels and morphologies. Crucial stresses frequently identified by the LCRA were depletion of dissolved oxygen (DO), disappearances of habitats (e.g. deep and shallow), disappearance of spawning area due to benthic deposition, and existence of obstructions in the streams. Most LCRA results regarding existence or non-existence of 15 fishes were in fairly good agreement with field survey or literature reviews results. From these results, we thought the present LCRA would be a useful tool in assessing crucial stress as well as in evaluating habitat conditions in steams, which could be used for the restoration of steams.

scholarly journals Contrasting impacts of pollen and seed dispersal on spatial genetic structure in the bird-pollinated Banksia hookeriana

Heredity ◽  
2008 ◽  
Vol 102 (3) ◽  
pp. 274-285 ◽  
Author(s):  
S L Krauss ◽  
T He ◽  
L G Barrett ◽  
B B Lamont ◽  
N J Enright ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Seed Dispersal ◽  
Spatial Genetic Structure ◽  
Pollen And Seed Dispersal

scholarly journals SELECTIVE INTERACTIONS BETWEEN SHORT-DISTANCE POLLEN AND SEED DISPERSAL IN SELF-COMPATIBLE SPECIES

Evolution ◽  
2006 ◽  
Vol 60 (11) ◽  
pp. 2257 ◽  
Author(s):  
Virginie Ravigné ◽  
Isabelle Olivieri ◽  
Santiago C. González-Martínez ◽  
François Rousset
Keyword(s):  
Seed Dispersal ◽  
Short Distance ◽  
Pollen And Seed Dispersal ◽  
Selective Interactions
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