The Evolution of Cooperation Sachs, Joel L.; Mueller, Ulrich G.; Wilcox, Thomas P. ...
The Quarterly Review of Biology,
06/2004, Letnik:
79, Številka:
2
Book Review, Journal Article
Recenzirano
Darwin recognized that natural selection could not favor a trait in one species solely for the benefit of another species. The modern, selfish‐gene view of the world suggests that cooperation between ...individuals, whether of the same species or different species, should be especially vulnerable to the evolution of noncooperators. Yet, cooperation is prevalent in nature both within and between species. What special circumstances or mechanisms thus favor cooperation? Currently, evolutionary biology offers a set of disparate explanations, and a general framework for this breadth of models has not emerged. Here, we offer a tripartite structure that links previously disconnected views of cooperation. We distinguish three general models by which cooperation can evolve and be maintained: (i)directed reciprocation—cooperation with individuals who give in return; (ii)shared genes—cooperation with relatives (e.g., kin selection); and (iii)byproduct benefits—cooperation as an incidental consequence of selfish action. Each general model is further subdivided. Several renowned examples of cooperation that have lacked explanation until recently—plant‐rhizobium symbioses and bacteria‐squid light organs—fit squarely within this framework. Natural systems of cooperation often involve more than one model, and a fruitful direction for future research is to understand how these models interact to maintain cooperation in the long term.
There is an exponentially increasing amount of human-associated litter in our oceans. This marine litter results in a wide range of potential impacts on the environment. These range from the ...introduction of adsorbed polychlorinated biphenyls (PCBs) into food webs to the entanglement and subsequent mortality of threatened seabirds, fish, turtles and mammals in anthropogenic litter and derelict fishing gear. While there has been a major effort afoot to publicize these issues, there remains a paucity of data and scientific research to underpin solutions to the problems. To address knowledge gaps and to identify potential solutions, we assembled thirteen experts from around the world who are leaders in the field. Speakers present current research in three major areas: 1) integrated ecological and oceanographic models to that measure risk to wildlife and predict impact, 2) literature reviews and field studies that measure both the scope and intensity of the threat across species, and 3) analysis of wildlife indicators as regulatory standards for plastic concentration in the environment.
•Nearly 700 marine species are known to interact with marine debris.•Experts rate fishing gear, balloons, plastic bags and bottle caps as most harmful to wildlife.•Even deep sea litter is ubiquitous, with up to items/ha on seamounts.•4500 nets likely killed more than 2.5 M marine invertebrates; 800,000 fish and 20,000 birds before removal.
One of the outstanding and poorly understood examples of cooperation between species is found in corals, hydras and jellyfish that form symbioses with algae. These mutualistic algae are mostly ...acquired infectiously from the seawater and, according to models of virulence evolution, should be selected to parasitize their hosts. We altered algal transmission between jellyfish hosts in the laboratory to examine the potential for virulence evolution in this widespread symbiosis. In one experimental treatment, vertical transmission of algae (parent to offspring) selected for symbiont cooperation, because symbiont fitness was tied to host reproduction. In the other treatment, horizontal transmission (infectious spread) decoupled symbiont fitness from the host, potentially allowing parasitic symbionts to spread. Fitness estimates revealed a striking shift to parasitism in the horizontal treatment. The horizontally transmitted algae proliferated faster within hosts and had higher dispersal rates from hosts compared to the vertical treatment, while reducing host reproduction and growth. However, a trade-off was detected between harm caused to hosts and symbiont fitness. Virulence trade-offs have been modelled for pathogens and may be critical in stabilising 'infectious' symbioses. Our results demonstrate the dynamic nature of this symbiosis and illustrate the potential ease with which beneficial symbionts can evolve into parasites.
Phylogenetic relationships among the species of true frogs (
Rana) from North, South, and Central America were investigated based on the sequences of approximately 2
kb from the mitochondrial genome, ...sampled from most of the described species, as well as eight undescribed species. This analysis, combined with previous studies of the phylogeny of New World
Rana, served as the basis for a revised classification of the group. The American species of
Rana are not monophyletic; the western North American
Amerana is more closely related to the
R. temporaria group of Eurasia (together, these frogs form the group
Laurasiarana). The remaining species from the Americas form the monophyletic group
Novirana, which includes:
R. sylvatica;
Aquarana (the
R. catesbeiana group);
Ranula (the
R. palmipes group, including the mostly upland
Levirana species and the mostly lowland
Lithobates species);
Torrentirana (the
R. tarahumarae group, or
Zweifelia, plus
R. sierramadrensis),
Stertirana (the
R. montezumae group, or
Lacusirana, plus
R. pipiens),
Nenirana (the
R. areolata group), and
Scurrilirana (most of the southern and tropical leopard frogs). The mitochondrial sequences supported many of the previous hypotheses of relationships of New World
Rana, although there were some differences involving the placement of the species
R. pipiens,
R. sierramadrensis, and
R. sylvatica. Parametric bootstrap analyses indicated significant support for the relationships inferred from the mtDNA sequences, and rejected the previous hypotheses of relationships for these three species.
Four New World genera of dwarf boas (
Exiliboa,
Trachyboa,
Tropidophis, and
Ungaliophis) have been placed by many systematists in a single group (traditionally called Tropidophiidae). However, the ...monophyly of this group has been questioned in several studies. Moreover, the overall relationships among basal snake lineages, including the placement of the dwarf boas, are poorly understood. We obtained mtDNA sequence data for 12S, 16S, and intervening tRNA–val genes from 23 species of snakes representing most major snake lineages, including all four genera of New World dwarf boas. We then examined the phylogenetic position of these species by estimating the phylogeny of the basal snakes. Our phylogenetic analysis suggests that New World dwarf boas are not monophyletic. Instead, we find
Exiliboa and
Ungaliophis to be most closely related to sand boas (Erycinae), boas (Boinae), and advanced snakes (Caenophidea), whereas
Tropidophis and
Trachyboa form an independent clade that separated relatively early in snake radiation. Our estimate of snake phylogeny differs significantly in other ways from some previous estimates of snake phylogeny. For instance, pythons do not cluster with boas and sand boas, but instead show a strong relationship with
Loxocemus and
Xenopeltis. Additionally, uropeltids cluster strongly with
Cylindrophis, and together are embedded in what has previously been considered the macrostomatan radiation. These relationships are supported by both bootstrapping (parametric and nonparametric approaches) and Bayesian analysis, although Bayesian support values are consistently higher than those obtained from nonparametric bootstrapping. Simulations show that Bayesian support values represent much better estimates of phylogenetic accuracy than do nonparametric bootstrap support values, at least under the conditions of our study.
— Knowledge of regolith depth structure is important for a variety of studies of the Moon and other bodies such as Mercury and asteroids. Lunar regolith depths have been estimated using morphological ...techniques (i.e., Quaide and Oberbeck 1968; Shoemaker and Morris 1969), crater counting techniques (Shoemaker et al. 1969), and seismic studies (i.e., Watkins and Kovach 1973; Cooper et al. 1974). These diverse methods provide good first order estimates of regolith depths across large distances (tens to hundreds of kilometers), but may not clearly elucidate the variability of regolith depth locally (100 m to km scale). In order to better constrain the regional average depth and local variability of the regolith, we investigate several techniques. First, we find that the apparent equilibrium diameter of a crater population increases with an increasing solar incidence angle, and this affects the inferred regolith depth by increasing the range of predicted depths (from ∼7–15 m depth at 100 m equilibrium diameter to ∼8–40 m at 300 m equilibrium diameter). Second, we examine the frequency and distribution of blocky craters in selected lunar mare areas and find a range of regolith depths (8–31 m) that compares favorably with results from the equilibrium diameter method (8–33 m) for areas of similar age (∼2.5 billion years). Finally, we examine the utility of using Clementine optical maturity parameter images (Lucey et al. 2000) to determine regolith depth. The resolution of Clementine images (100 m/pixel) prohibits determination of absolute depths, but this method has the potential to give relative depths, and if higher resolution spectral data were available could yield absolute depths.
Summary
Background
Psoriasis is an inflammatory skin disease that may be associated with an adverse cardiometabolic profile including modulated plasma adiponectin and leptin levels. Whether these ...levels are independent of cardiometabolic risk factors, which are also prevalent in psoriasis, is not known.
Methods
A consecutive sample of 122 participants with varying degrees of psoriasis severity, and a random sample of 134 participants without psoriasis, were recruited for this case–control study. Cardiometabolic risk factors including traditional cardiovascular risk factors, waist circumference, insulin resistance, and total plasma adiponectin and leptin were measured. Total plasma adiponectin and leptin levels were compared in unadjusted and adjusted analyses by psoriasis status.
Results
Participants with psoriasis had mostly mild disease and were mainly on topical therapies, but still had a more adverse cardiometabolic profile compared with those without psoriasis. Furthermore, plasma adiponectin levels were significantly lower in participants with psoriasis than those without {7.13 μg/mL interquartile range (IQR) 4.9–11.3) vs. 14.5 μg/mL (IQR 8.4–24.1); P < 0.001}. Plasma leptin (ng/mL) levels were higher in the psoriasis group but this did not reach statistical significance 11.3 (IQR 6.4–21.8) vs. 9.8 (IQR 4.9–20.5); P = 0.07. In multivariable modelling, plasma adiponectin levels were still negatively associated with psoriasis status after adjusting for waist size (% difference = −41.2%, P < 0.001), insulin resistance (% difference = −39.5%, P < 0.001), and both waist size and insulin resistance (% difference = −38.5%, P < 0.001).
Conclusions
Plasma levels of adiponectin were lower in psoriasis, and this relationship persisted after adjusting for cardiometabolic risk factors known to decrease adiponectin levels. These findings suggest that inflammation present in psoriasis may be associated with adipose tissue dysfunction; however, direct studies of adipose tissue are needed to confirm this.
Introduction
Decision regret (DR) may occur when a patient believes their outcome would have been better if they had decided differently about their management. Although some studies investigate DR ...after treatment for localised prostate cancer, none report DR in patients undergoing surgery and post‐prostatectomy radiotherapy. We evaluated DR in this group of patients overall, and for specific components of therapy.
Methods
We surveyed 83 patients, with minimum 5 years follow‐up, treated with radical prostatectomy (RP) and post‐prostatectomy image‐guided intensity‐modulated radiotherapy (IG‐IMRT) to 64–66 Gy following www.EviQ.org.au protocols. A validated questionnaire identified DR if men either indicated that they would have been better off had they chosen another treatment, or they wished they could change their mind about treatment.
Results
There was an 85.5% response rate, with median follow‐up post‐IMRT 78 months. Adjuvant IG‐IMRT was used in 28% of patients, salvage in 72% and ADT in 48%. A total of 70% of patients remained disease‐free. Overall, 16.9% of patients expressed DR for treatment, with fourfold more regret for the RP component of treatment compared to radiotherapy (16.9% vs 4.2%, P = 0.01). DR for androgen deprivation was 14.3%. Patients were regretful of surgery due to toxicity, not being adequately informed about radiotherapy as an alternative, positive margins and surgery costs (83%, 33%, 25% and 8% of regretful patients respectively). Toxicity caused DR in the three radiotherapy‐regretful and four ADT‐regretful patients. Patients were twice as regretful overall, and of surgery, for salvage vs adjuvant approaches (both 19.6% vs 10.0%).
Conclusion
Decision regret after RP and post‐prostatectomy IG‐IMRT is uncommon, although patients regret RP more than post‐operative IG‐IMRT. This should reassure urologists referring patients for post‐prostatectomy IG‐IMRT, particularly in the immediate adjuvant setting. Other implications include appropriate patient selection for RP (and obtaining clear margins), and ensuring adequately discussing definitive radiotherapy as an alternative to surgery.
Both dose-escalated external beam radiotherapy (DE-EBRT) and androgen deprivation therapy (ADT) improve the outcomes in patients with intermediate-risk prostate cancer. Despite this, there are only ...few reports evaluating DE-EBRT for patients with intermediate-risk prostate cancer receiving neoadjuvant ADT, and virtually no studies investigating dose escalation >74 Gy in this setting. We aimed to determine whether DE-EBRT >74 Gy improved the outcomes for patients with intermediate-risk prostate cancer who received neoadjuvant ADT.
In our institution, patients with intermediate-risk prostate cancer were treated with neoadjuvant ADT and DE-EBRT, with doses sequentially increasing from 74 Gy to 76 Gy and then to 78 Gy between 2006 and 2012. We identified 435 patients treated with DE-EBRT and ADT, with a median follow-up of 70 months. For the 74 Gy, 76 Gy, and 78 Gy groups, five-year biochemical disease-free survival rates were 95.0%, 97.8%, and 95.3%, respectively; metastasis-free survival rates were 99.1%, 100.0%, and 98.6%, respectively; and prostate cancer-specific survival rate was 100% for all three dose levels. There was no significant benefit for dose escalation either on univariate or multivariate analysis for any outcome.
There was no benefit for DE-EBRT >74 Gy in our cohort of intermediate-risk prostate cancer patients treated with neoadjuvant ADT. Given the higher risks of toxicity associated with dose escalation, it may be feasible to omit dose escalation in this group of patients. Randomized studies evaluating dose de-escalation should be considered.
Introduction
We compare the results of modern external‐beam radiotherapy (EBRT), using combined androgen deprivation and dose‐escalated intensity‐modulated radiotherapy with MRI‐CT fusion and daily ...image guidance with fiducial markers (DE‐IG‐IMRT), with recently published Australian series of brachytherapy and surgery.
Methods
Five‐year actuarial biochemical disease‐free survival (bDFS), metastasis‐free survival (MFS) and prostate cancer‐specific survival (PCaSS) were calculated for 675 patients treated with DE‐IG‐IMRT and androgen deprivation therapy (ADT). Patients had intermediate‐risk (IR) and high‐risk (HR) disease. A search was conducted identifying Australian reports from 2005 onwards of IR and HR patients treated with surgery or brachytherapy, reporting actuarial outcomes at 3 years or later.
Results
With a median follow‐up of 59 months, our 5‐year bDFS was 93.3% overall: 95.5% for IR and 91.3% for HR disease. MFS was 96.9% overall (99.0% IR, 94.9% HR), and PCaSS was 98.8% overall (100% IR, 97.7% HR). Prevalence of Grade 2 genitourinary and gastrointestinal toxicity at 5 years was 1.3% and 1.6%, with 0.3% Grade 3 genitourinary toxicity and no Grade 3 gastrointestinal toxicity. Eight reports of brachytherapy and surgery were identified. The HDR brachytherapy series' median 5‐year bDFS was 82.5%, MFS 90.0% and PCaSS 97.9%. One surgical series reported 5‐year bDFS of 65.5% for HR patients. One LDR series reported 5‐year bDFS of 85% for IR patients.
Conclusions
Modern EBRT is at least as effective as modern Australian surgical and brachytherapy techniques. All patients considering treatment for localised prostate cancer should be referred to a radiation oncologist to discuss EBRT as an equivalent option.
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