Comparative study of the life cycles of six species of Dinotoperla (Plecoptera: Gripopterygidae) in Victoria

1985 ◽  
Vol 36 (5) ◽  
pp. 717 ◽  
Author(s):  
C Yule
Keyword(s):  
Comparative Study ◽  
Life Span ◽  
Early Summer ◽  
Life Cycles ◽  
Temporary Pools ◽  
Severe Drought

The life cycles of six species of Dinotoperla were studied. One of these, D. bassae, only occurred in temporary pools; three species, D. thwaitesi, D. fontana and D. brevipennis, were found in intermittently flowing creeks; and these three species as well as D. eucumbene and D. christinae inhabited cool, permanent rivers. All the species were univoltine (except for D. eucumbene, which had a nymphal life span of 11-15 months). D. bassae, D. brevipennis, D. christinae and D. eucumbene had seasonal well-synchronized life cycles, although in times of severe drought the eggs of D. bassae may remain in diapause for 18 months or more. Emergence periods of all species were relatively restricted and were completed by early summer.

Parasite adaptation to extreme conditions in a desert environment

Parasitology ◽  
1999 ◽  
Vol 119 (S1) ◽  
pp. S31-S56 ◽  
Author(s):  
R. C. Tinsley
Keyword(s):  
Life Span ◽  
Age Structure ◽  
Sonoran Desert ◽  
Experimental Studies ◽  
Rare Event ◽  
Life Cycles ◽  
Parasite Population ◽  
Severe Drought ◽  
Desert Environment ◽  
The Impact

SUMMARYDeserts represent universally recognized extreme environments for animal life. This paper documents the highly specialized adaptations of Pseudodiplorchis americanus, a monogenean parasite of the desert toad, Scaphiopus couchii. Building on a long-term record of parasite population ecology (continuing since the early 1980s), field studies focus on the effects of severe drought in the Sonoran Desert, Arizona, in the mid 1990s. This provides a test of the ability of the host-parasite system to tolerate exceptional perturbation. The analysis provides new insight into parasite infection dynamics in a natural wildlife system through integration of host and parasite population age structure. The environmental check interrupted host recruitment in 1993–95 and parasite recruitment in 1995–97. This produced an imprint in age structure and infection levels recognizable over several years: parasite recruitment failure reduced transmission 2–3 years later. The host (maximum life span 17 years) tolerated the disruption but the impact was more serious for the parasite (life span 3 years) leading to extinction of some previously stable populations. Despite this demonstration of a rare event exacerbating external environmental constraints, experimental studies suggest that the internal (host) environment normally creates the most severe conditions affecting P. americanus. Only about 3 % of parasites survive from invasion until first reproduction. Post-invasion factors including host immunity, characteristic of most parasite life cycles, constitute a greater constraint upon survival than external conditions, even in a desert environment.

The Lympho-Hemopoietic Organs of the Anadromous Sea Lamprey,Petromyzon marinus.A Comparative Study throughout its Life Span

1984 ◽  
Vol 65 (1) ◽  
pp. 1-15 ◽  
Author(s):  
C.F. Ardavin ◽  
R.P. Gomariz ◽  
M.G. Barrutia ◽  
J. Fonfria ◽  
A. Zapata
Keyword(s):  
Comparative Study ◽  
Life Span ◽  
Sea Lamprey ◽  
Hemopoietic Organs

scholarly journals A COMPARATIVE STUDY ON THE KINDS OF WEEDS OF PALM Plantations IN Tabuk AND Al-Qassim Regions IN Saudi Arabia

2021 ◽  
Vol 52 (3) ◽  
pp. 763-773
Author(s):  
N. A. Al-Harbi
Keyword(s):  
Saudi Arabia ◽  
Comparative Study ◽  
Data Management ◽  
Life Span ◽  
Life Form ◽  
Date Palm ◽  
Arabian Peninsula ◽  
Severe Damage ◽  
Common Life ◽  
Unique Species

This study was aimed to investigate weeds kind in palm plantations. Date palm is the most chief economic crop in most countries of the Arabian Peninsula. Many factors, such as the presence of weeds, may cause a huge loss in the production of dates. Despite the severe damage caused by the presence of some weeds in agroecosystems, many weeds have many medicinal and economic uses. A total of 62 species were listed in palm Plantations in Tabuk and Al-Qassim Regions. A total of 51 species were listed in Tabuk Region (The number of unique species in the Tabuk Region reached 32 that not recorded in Al-Qassim Region. Also, 19 species were recorded in both of Tabuk and Al-Qassim Regions). A total of 30 weeds were listed in Al-Qassim Region (The number of unique species in the Al-Qassim Region reached 11 that not recorded in the Tabuk Region. In addition to, 19 species were recorded in both of Tabuk and Al-Qassim Regions). Zygophyllaceae was the most common family, the majority life span was annuals and the most common life form was therophyte in both Tabuk and Al-Qassim Regions. Data management and classification were achieved using PCORD (TWINSPAN and DCA analyses).

scholarly journals Linkages between Climate, Radial Growth and Defoliation in Abies pinsapo Forests from Southern Spain

Forests ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 1002
Author(s):  
Rafael M. Navarro-Cerrillo ◽  
Antonio Gazol ◽  
Carlos Rodríguez-Vallejo ◽  
Rubén D. Manzanedo ◽  
Guillermo Palacios-Rodríguez ◽  
...  
Keyword(s):  
Tree Ring ◽  
Radial Growth ◽  
Early Summer ◽  
Southern Spain ◽  
Tree Age ◽  
Severe Drought ◽  
Recent Climate ◽  
Tree Ring Data ◽  
Abies Pinsapo ◽  
Old Trees

Systematic forest networks of health monitoring have been established to follow changes in tree vigor and mortality. These networks often lack long-term growth data, but they could be complemented with tree ring data, since both defoliation and radial growth are proxies of changes in tree vigor. For instance, a severe water shortage should reduce growth and increase tree defoliation in drought-prone areas. However, the effects of climatic stress and drought on growth and defoliation could also depend on tree age. To address these issues, we compared growth and defoliation data with recent climate variability and drought severity in Abies pinsapo old and young trees sampled in Southern Spain, where a systematic health network (Andalucía Permanent Plot Network) was established. Our aims were: (i) to assess the growth sensitivity of old and young A. pinsapo trees and (ii) to test if relative changes in radial growth were related with recent defoliation, for instance, after severe droughts. We also computed the resilience indices to quantify how old and young trees recovered growth after recent droughts. Wet-cool conditions during the prior autumn and the current early summer improved the growth of old trees, whereas late-spring wet conditions enhanced the growth of young trees. Old trees were more sensitive to wet and sunny conditions in the early summer than young trees. Old and young trees were more responsive to the Standardized Precipitation-Evapotranspiration Index drought index of June–July and July–August calculated at short (one–three months) and mid (three–six months) time scales, respectively. Old trees presented a higher resistance to a severe drought in 1995 than young trees. A positive association was found between stand defoliation and relative growth. Combining monitoring and tree ring networks is useful for the detection of early warning signals of dieback in similar drought-prone forests.

Life cycles of four species of Pseudocalanus in Nova Scotia

1989 ◽  
Vol 67 (3) ◽  
pp. 552-558 ◽  
Author(s):  
I. A. McLaren ◽  
Estelle Laberge ◽  
C. J. Corkett ◽  
J.-M. Sévigny
Keyword(s):  
Life Cycle ◽  
Nova Scotia ◽  
First Generation ◽  
Early Summer ◽  
Life Cycles ◽  
The Arctic ◽  
Late Winter ◽  
Early Winter ◽  
Temperature Dependent ◽  
Scotian Shelf

The primarily arctic Pseudocalanus acuspes, relict in Bedford Basin, Nova Scotia, produces a first generation (G1) in late winter; most G1 individuals mature in late spring. The G1 then produces a G2, most of which "rest" in copepodite stages III and IV until early winter. These stages store large amounts of lipid in early summer, which slowly diminish subsequently. A small number of G2 individuals continue to develop at temperature-dependent rates, maturing in early autumn and producing G3 adults in November. Copepodites developing in winter and spring store less lipid. The primarily arctic Pseudocalanus minutus, rare in Bedford Basin and on the Scotia Shelf, is strictly annual, developing to a lipid-filled copepodite stage V after spawning in late winter. The arctic–temperate Pseudocalanus newmani is abundant on the Scotian Shelf, but may not be self-sustaining when advected into Bedford Basin. It stores little lipid and appears to have at least three mature generations at temperature-dependent intervals over Browns Bank between May and November. It may rest in winter, or its life-cycle synchrony by spring could result from food-limited development during winter. The temperate Pseudocalanus moultoni appears to have a life cycle similar to that of P. newmani, but was less common during summer on Browns Bank. These life cycles are appropriately adapted to the geographical ranges of the species, and show some parallels with species of Calanus.

Demography of three perennial grasses in a central Queensland eucalypt woodland

2009 ◽  
Vol 31 (4) ◽  
pp. 427 ◽  
Author(s):  
P. Jones ◽  
P. Filet ◽  
D. M. Orr
Keyword(s):  
Life Span ◽  
Seedling Recruitment ◽  
Negative Impact ◽  
Grazing Pressure ◽  
Perennial Grasses ◽  
Seasonal Rainfall ◽  
Severe Drought ◽  
Heteropogon Contortus ◽  
Heavy Grazing ◽  
Eucalypt Woodland

The population dynamics of the palatable, perennial grasses Bothriochloa ewartiana (Domin) C.E.Hubb. (desert Mitchell grass), Chrysopogon fallax S.T.Blake (golden beard grass) and Heteropogon contortus (L.) P.Beauv. ex Roem. & Schult. (black speargrass), were studied in an extensive grazing study conducted in a eucalypt woodland within the Aristida–Bothriochloa pasture community in central Queensland between 1994 and 2000. Treatments were three grazing pressures based on light, medium and heavy utilisation of forage available at the end of summer and two timber treatments (trees intact and trees killed). Seasonal rainfall throughout this study was generally favourable for plant growth with no severe drought periods. Grazing pressure had a greater overall impact on plant dynamics than timber treatment, which had minimal impact. Grazing pressure had a large impact on H. contortus dynamics, an intermediate impact on B. ewartiana and no impact on C. fallax. Fluctuations in plant density of both B. ewartiana and C. fallax were small because both species were long lived with low levels of seedling recruitment and plant death, whereas fluctuations in H. contortus density were relatively high because of its relatively short life span and higher levels of both recruitment and death. Heavy grazing pressure increased the recruitment of B. ewartiana and H. contortus in some years but had no impact on that of C. fallax. Heavy grazing pressure reduced the survival of the original plants of both B. ewartiana and H. contortus but not of C. fallax. For H. contortus, the size of the original plants was larger where trees were killed than where trees were left intact and plants of the 1995 seedling cohort were larger in 1998 at heavy compared with those at light and medium grazing pressure. Grazing had a minor negative impact on the soil seed bank of H. contortus. Populations of all three species remained stable throughout this study, although the favourable seasonal rainfall experienced and the short duration of this study relative to the life span of these species may have masked longer term, deleterious impacts of heavy grazing pressure.

Age Profiles in Elephant and Mammoth Bone Assemblages

1985 ◽  
Vol 24 (3) ◽  
pp. 333-345 ◽  
Author(s):  
Gary Haynes
Keyword(s):  
United States ◽  
Comparative Study ◽  
Late Pleistocene ◽  
Loxodonta Africana ◽  
African Elephant ◽  
Severe Drought ◽  
Southwestern United States ◽  
Drought Conditions ◽  
Tentative Interpretation ◽  
Sample Age

Age profiles of modern African elephant (Loxodonta africana) populations are significantly affected by drought conditions that cause local die-offs. Subadult animals die in proportions that may be nearly twice what is recorded in live populations. Such biasing of death sample age profiles might also have occurred during late Pleistocene die-offs of Mammuthus. This comparative study of modern and fossil proboscidean age structures supports a tentative interpretation that late Pleistocene extinction of Mammuthus (at least in the southwestern United States) resulted from severe drought conditions, at which Clovis hunters were witnesses, but not necessarily frequent participants.

Comparative study of the life cycles ofAlexandrium tamutumandAlexandrium minutum(Gonyaulacales, Dinophyceae) in culture1

2007 ◽  
Vol 43 (5) ◽  
pp. 1039-1053 ◽  
Author(s):  
Rosa Isabel Figueroa ◽  
Esther Garcés ◽  
Isabel Bravo
Keyword(s):  
Comparative Study ◽  
Life Cycles
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